Effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women: study protocol for a double-blinded randomized controlled trail.

Suvarna Hebbar; Shashikiran Umakanth; Latha Thimmappa; Joniya Galbao

doi:10.12688/f1000research.147438.1

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Study Protocol

Effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women: study protocol for a double-blinded randomized controlled trail.

[version 1; peer review: 1 not approved]

Suvarna Hebbar ¹, Shashikiran Umakanth², Latha Thimmappa³, Joniya Galbao⁴

PUBLISHED 26 Apr 2024

Author details Author details

¹ Clinical Nutrition and Dietetics, Manipal College of Health Professions, Manipal., Karnataka, 576104, India
² Department of Medicine, Melaka Manipal Medical College, Manipal, Karnataka, 576104, India
³ College of Nursing, AIIMS Kalyani, Basantapur, West Bengal, 741245, India
⁴ Clinical Nutrition and Dietetics, Kasturba Hospital, Manipal, Karnataka, 576104, India

Suvarna Hebbar
Roles: Conceptualization, Funding Acquisition, Investigation, Resources, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Shashikiran Umakanth
Roles: Conceptualization, Methodology, Supervision, Validation, Writing – Review & Editing

Latha Thimmappa
Roles: Conceptualization, Formal Analysis, Methodology, Supervision, Validation, Writing – Review & Editing

Joniya Galbao
Roles: Conceptualization, Writing – Review & Editing

OPEN PEER REVIEW

REVIEWER STATUS

This article is included in the Manipal Academy of Higher Education gateway.

Abstract

Background

Obesity is a major consequence of malnutrition and significantly contributes to the global burden of chronic diseases. Currently, there are more overweight and obese individuals than underweight individuals. Increased fiber intake can increase insulin sensitivity and fat oxidation. According to research studies, the average dietary fiber consumption is below the recommended value, and the WHO anticipates that the worldwide obesity prevalence has increased in the past ten years.

Aim

To evaluate the effect of high dietary fiber intake on insulin resistance, body composition, and weight in overweight and obese middle-aged women.

Method

This hospital-based study evaluated 500 people during phase 1 to identify the prevalence of insulin resistance among overweight and obese middle-aged women. An RCT with intervention and control arms for 180 individuals is being conducted in Phase 2 to determine the effect of increased dietary fiber consumption on insulin resistance, body composition, and weight in overweight or obese middle-aged women. In the intervention group, women were counselled for 15 min and given a tailored food chart including 40 g of fiber. Women in the control arm will receive a typical food care plan with 25 g of fiber, based on their health status. Each engaged woman received fiber nutritional empowerment.

Discussion

Increasing dietary fiber consumption can improve insulin resistance, body composition, and weight in middle-aged overweight and obese women.

Trial registration

The Clinical Trials Registry of India (CTRI/2022/01/039074) has registered this study as a clinical trial on January 3, 2022 http://ctri.nic.in

Keywords

Middle Aged, Women, Insulin Resistance, Overweight, Obesity, Body Composition, Dietary Fiber, Health Status.

Corresponding author: Suvarna Hebbar

Competing interests: No competing interests were disclosed.

Grant information: This study is funded by IMCR-DHR (R.11014/12/2023-GIA/HR)
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2024 Hebbar S et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

How to cite: Hebbar S, Umakanth S, Thimmappa L and Galbao J. Effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women: study protocol for a double-blinded randomized controlled trail. [version 1; peer review: 1 not approved]. F1000Research 2024, 13:396 (https://doi.org/10.12688/f1000research.147438.1) First published: 26 Apr 2024, 13:396 (https://doi.org/10.12688/f1000research.147438.1) Latest published: 26 Apr 2024, 13:396 (https://doi.org/10.12688/f1000research.147438.1)

Background

Obesity is a major public health concern worldwide. Urbanization, economic growth, changing lifestyles, and dietary habits have posed a “double burden” of diseases in rapidly developing low- and middle-income countries, such as India.¹ The average dietary fiber consumption was below the recommended value as per research studies, and the World Health Organization estimates that the incidence of obesity has increased worldwide in the last 10 years. Most people do not consume enough food with adequate amounts of fiber to meet the recommended level, and obese women report a lower intake of dietary fiber than normal-weight individuals.² A rich source of dietary fiber in meals induces satiety, resulting in reduced hunger.³ The effect of dietary fiber was obvious in obese participants.⁴ According to a study led by Georgia State University, consumption of dietary fiber promotes the growth of beneficial bacteria in the colon, preventing obesity, metabolic syndrome, and adverse changes in the intestine.⁵

The decreased incidence of several diseases is associated with fiber-rich diets that have a positive impact on well-being. High-fiber foods can replace energy (calories), which provides low energy density against high-fat foods. The roughage and thickening properties of dietary fiber primarily influence satiation and fullness of the stomach. People who consume ample amounts of dietary fiber are at a low risk of developing coronary artery diseases, stroke, hypertension, diabetes, obesity, and certain gastrointestinal diseases compared to those who have minimal fiber intake. A significant improvement was observed in the values of serum lipoprotein and blood pressure, improvement in blood sugar for diabetic entities, and weight reduction by improving the consumption of elevated fiber foods or fiber supplements. Ingestion of soluble fiber enhances immune function.⁶

An increase in the consumption of dietary fiber from a variety of fruits, vegetables, legumes, and whole-grain products will provide various physiological benefits. Dietary fiber, if consumed in acceptable amounts, lowers the risk of several chronic disorders, such as cardiovascular diseases, type 2 diabetes mellitus, obesity, and certain types of cancer. Dietary fiber sources, along with functional fibers, have the additional benefit of organically occurring micronutrients and phytochemicals that may enhance human health. Health benefits of consuming dietary fiber must be actively communicated to the public.⁷ There are few studies on the utilization of dietary fiber in the treatment of obesity, but further research is required to confirm stronger associations between dietary fiber and obesity.⁸ The growth of beneficial bacteria in the gut is initiated by dietary fiber. Increased consumption of dietary fiber and whole grains helps normalize gut microbiota symbiosis. Dietary fiber improves the gut microbiota composition in individuals with obesity and other metabolic diseases. Nutritive fiber has different impacts on the gut microbiota because of the diverse compositions and structures of the fibers and whole grains.⁹ High-dietary fiber food is more satiating and has a significant role in establishing a sense of contentment, aids in reducing serum insulin secretion, helps in gastric emptying time, and reduces food intake. It also assists in increasing satiety levels, fat oxidation, decreasing energy intake, and lowering body fat content.¹⁰ Dietary fiber, upon fermentation, generates small chain fatty acids that alter eating forms by circulating peptides and gut hormones such as cholecystokinin and glucagon-like peptides, which reduce hunger and promote satiety.¹¹ Insulin sensitivity and stimulation of fat oxidation can be improved by increasing fiber intake. Saliva and gastric juice secretions distend the stomach by promoting satiety by enhancing chewing limits.¹²

This study focuses on weight reduction by increasing fiber consumption. Recommended fiber intake of 40 2000 kcal is per the Indian Council of Medical Research and National Institute of Nutrition Guidelines.¹³ Dietary fiber has various health benefits, with a satiating role in establishing a sense of contentment, lowering cholesterol levels, and decreasing the rise in blood sugar and fat oxidation by lowering body fat content. Consumption of dietary fiber at the recommended amount will improve overall well-being.

Objectives

Primary objective

• To determine the effect of fiber intake on insulin resistance, body composition, and weight.

Secondary objective

• To determine the effect of fiber intake on biochemical parameters
• To assess the opinions of women on modified fiber intake

Methods

The present study will be conducted in the OPDs of the medicine, gynaecology, and endocrinology units of a tertiary care hospital in Karnataka, India. This study: 519/2021 was approved by Kasturba Medical College and Kasturba Hospital Institutional Ethics Committee (IEC) on December 19, 2021. The data will be collected on the consent of the patients and the confidentiality will be strictly maintained. Women in the age group between 35-55 years will be screened for insulin resistance at Phase-1 and those women with no contraindication for high fiber consumption and abnormal HOMA-IR will be included in Phase-2. Baseline assessments will be performed for each woman in both the intervention and control groups. Demographic data will be collected, including age, religion, place of residence, type of family, number of family members, marital history, education, occupation, and income performance. Anthropometric data obtained using a stadiometer (for measuring height), weighing scale (for weight measurement), and measuring tape for waist circumference and hip circumference will be documented in the OPD. In the biochemical data, fasting blood glucose (hexokinase method) HbA1c (TINA), serum insulin (ECLIA) and lipid profile (triglyceride-GPO Trinder, HDL-direct homogenous, LDL enzymatic, total cholesterol-CE-CHOD-POD) will be checked. To assess dietary data, a 24-hr dietary recall and food frequency questionnaire was used. The data will be analysed using Diet Cal version 6.3. Physical activity data were assessed using the GPAQ (Global Physical Activity Questionnaire). Body fat analyzer was used to assess visceral fat, subcutaneous fat, and muscle mass. Clinical assessment (physical complaints such as bowel movement, satiety, leg pain, and backache) will be performed. Dietary advice was communicated to both the control and intervention groups. This study involves a minimal risk of drawing 10 ml blood thrice, discomfort related to high fiber diet and minimal physical examination. The study will help in increasing the awareness level of intake of fibre in women which will there by improve the nutritional status and quality of life.

Study design

This study was single-center, stratified, randomized, controlled, and double-blind. In the first phase, a cross-sectional study will be conducted to identify the prevalence of insulin resistance among overweight and obese middle-aged women. Two groups, with at least 166 in each group of overweight and obese will be screened and in second phase a randomized clinical trial will be conducted to find the effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women. For this purpose, women with no contraindications for high fiber consumption or abnormal HOMA-IR were included. Simultaneously, an in-depth interview will be conducted telephonically for 45 min to understand the barriers of fiber intake among two equal groups of 20 each, consuming low fiber (< 20 g) and good fiber (= 20 g to 25 g) in phase 1.

Study setting

This study will be carried out in the OPDs of the medicine, gynaecology, and endocrinology units of a tertiary care hospital in Karnataka, India.

Sample size

At Phase 1, a total of 500 women will be screened to identify the prevalence of insulin resistance among overweight and obese middle-aged women. Two groups, with at least 166 in each group of overweight and obese will be screened. The sample size was calculated in accordance with insulin resistance and BMI.¹¹ Simultaneously, in Phase 2, the sample size was 180 participants,¹² who will be randomized into the study and control groups. Stratified Block Randomization,9 block with 20 in each (stratified based on overweight and obese with at least 60 participants in overweight and obese strata). Sequence generation of samples using online software and the Concealment-Opaque Envelope Method will be applied to identify the effect of high dietary fiber intake on insulin resistance, body composition, and weight among overweight or obese middle-aged women.

Sample size calculation

Sample size for repeated measures ANOVA.

Drop out 15%

n = \frac{2 * (Z_{1} α / 2 + Z_{1} - β)^{2} * s^{2} * [1 + (m - 1)] * ρ}{m * d^{2}}

Where,

n = sample size

z_1-α/2 = 1.96 at α = 0.05

z_1-β = 0.84 at 80% power

s = anticipated population standard deviation of the outcome variable.

d = clinically significant difference

m = number of time points/follow-ups = 2

ρ = intraclass correlation = 0.4

Insulin resistance

n = 71

Accounting for a dropout rate of 15%, n = 83 per group

As per BMI

n = 77

Accounting for a dropout rate of 15%, n = 90 per group

The final required sample size was 180 (90 each in the intervention and control groups).

Participants

Inclusion criteria – Phase-1

• Women willing to give consent.
• Middle-aged women of the age group 35-55 yrs.
• Women with BMI ≥ 23 kg/m² (Overweight- 23-24.9 kg/m², Obese: ≥30 kg/m²)

Exclusion criteria – Phase-1

• Women with any disorder that affects their nutritional status, such as tuberculosis, HIV, cancer, and organ failure.
• Women with type 2 diabetes mellitus
• Women with hypertension, thyroid disorders, or other medical conditions started on any medication that could affect body weight (including thyroxine, antithyroid medications, and diuretics) after enrolment in the study.
• Pregnant or lactating women.
• Women with contraindications for high fiber consumption, for example inflammatory bowel disease.
• Women already following a weight loss regime.
• Women consuming fiber more than the recommended dietary allowance.

Inclusion criteria – Phase-2

• Abnormal HOMA-IR (>2) indicating insulin resistance.
• Willingness to follow high fiber diet as recommended if randomized to intervention arm.

Exclusion criteria – Phase-2

• Not willing to participate further in the study.
• Not willing to follow the high fiber diet as recommended.

Sampling techniques: At baseline, 500 women will be screened to identify the prevalence of insulin resistance among overweight and obese middle-aged women.

Phase-1, Two groups, with at least 166 in each group of overweight and obese will be screened and tested for insulin resistance.

Phase-2, Overweight and obese participants with abnormal insulin resistance will be randomized into study and control groups.

Randomization and allocation

Stratified Block Randomization consisted of 9 blocks with 20 participants each (stratified by overweight and obese, with at least 60 participants in each stratum). Sample sequence creation will be performed using online software. The Allocation Concealment-Opaque Envelope Method was applied.

Data collection

Intervention group

All women in the intervention arm will be counselled for about 15 min with a customized diet chart consisting of a high fiber of 40 g. Nutritional empowerment of fiber should be delivered to each enrolled woman. Necessary dietary advice on the modified diet plan and motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling session, on the 15^th day, women will be telephonically assessed on their 24hr recall dietary intake. On the 30^th day, the women will be contacted telephonically again to record their 24hr recall of their dietary intake. Necessary dietary changes in the modified diet plan would be advised, and the motivation to adhere to the diet plan will be continued. On the 60^th day, the women will be again telephonically contacted to record their 24hr recall on their dietary intake, necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90^th day, as an outcome-based assessment, women will be referred to the hospital for anthropometric data, biochemical data followed by dietary data, 24hr dietary recall, food frequency analyzed using Diet Cal version 6.3, physical activity data assessed using GPAQ, body fat analyzed using a body fat analyzer, and a questionnaire on patient opinion regarding modified diet plan. For motivation and adherence to fiber consumption, subjects will be communicated telephonically on the 135^th day. From the 136^th to 180^th days, there was no conversation regarding dietary modifications. On the 180^th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data. 24hr dietary recall, food frequency analyzed using Diet Cal version 6.3, physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group

Women in the control arm will receive a traditional diet care plan with 25 g of fiber, according to their health condition. Necessary dietary advice was communicated to the control group during their first visit to the hospital. There was no telephonic communication with the control group until the 90^th day. On the 90^th day, as an outcome-based assessment, women will be referred to the hospital for anthropometric data, biochemical data, dietary data, 24hr dietary recall, food frequency analyzed using Diet Cal version 6.3, physical activity data assessed using GPAQ, and body fat analyzed using a body fat analyzer. On the 180^th day, as a compliance-checking, the patient will be again called to the hospital for anthropometric data, biochemical data, dietary data, 24-hr dietary recall, food frequency analyzed using Diet Cal version 6.3, physical activity data assessed using GPAQ, and body fat analyzed using a body fat analyzer.

Statistics analysis

The intervention arm will be compared against the control arm for all the primary analysis. We will use the chi-square test for primary outcomes and the t-test for continuous outcomes.

Study status

Currently, participants have been recruited for phase-1 and 2, and follow-up for phase-2 is ongoing.

Discussion

There is limited evidence on the beneficial association between high dietary fiber intake and metabolic indicators, body composition, and weight in middle-aged women who are overweight or obese in the Indian population. This study will focus on improving insulin resistance, body composition, and weight, which will be recorded in participants with high dietary fiber intake. Dietary fiber has various health benefits, with a satiating role in establishing a sense of contentment, lowering cholesterol levels, and decreasing the rise in blood sugar and fat oxidation by lowering body fat content.

Article summary

Strengths and limitations of this study

• An improvement in insulin resistance, body composition, and weight will be recorded in participants with high dietary fiber intake.
• Good knowledge and practice regarding modified diet plans with high dietary fiber will be addressed to participants.
• Knowledge regarding barriers/consequences/clinical hindrances in consuming a high-fiber diet will be addressed.
• Drop out due to non-compliance
• Patients adhering to follow the diet plan for a longer period
• Limited resources are available to address the importance of inclusion of recommended fiber in the general public since we are only screening patients visiting hospitals.

Ethics and dissemination

The study protocol was reviewed and approved by the Institutional Research Committee (IRC) and Institutional Ethics Committee (IEC): 519/2021 was approved by Kasturba Medical College and Kasturba Hospital Institutional Ethics Committee on December 19, 2021, registered under the Clinical Trials Registry- India (CTRI) (CRTI/2022/01/039074). The study will be carried out in compliance with Good Clinical Practice standards. These findings will be published in peer-reviewed journals and presented at international conferences.

Consent to participate

All the participants signed a written informed consent form. All methods will be carried out in accordance with the relevant guidelines and regulations.

Data availability

Underlying data

No data are associated with this article.

Extended data

Open Source Framework: Effect of high dietary fiber intake on insulin resistance, body composition, and weight among overweight or obese middle-aged women: Study protocol for a double-blind randomized controlled trial, DOI https://doi.org/10.17605/OSF.IO/HUW43.

The supplementary materials available are:

‐ Questionnaire
‐ SPIRIT checklist
‐ Education Material

Reporting guidelines

Open Source Framework: Checklist for Effect of high dietary fiber intake on insulin resistance, body composition, and weight among overweight or obese middle-aged women: Study protocol for a double-blinded randomized controlled trial, DOI https://doi.org/10.17605/OSF.IO/HUW43.

Acknowledgements

We are grateful to the funding agency IMCR-DHR, India.

References

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2. Namazi N, Larijani B, Azadbakht L: Are Isolated and Complex Fiber Supplements Good Choices for Weight Management? A Systematic Review. Arch. Iran. Med. 2017; 20(11): 704–713. PubMed Abstract
3. Delzenne NM, Cani PD: A place for dietary fibre in the management of the metabolic syndrome. Curr. Opin. Clin. Nutr. Metab. Care. 2005; 8(6): 636–640. PubMed Abstract | Publisher Full Text
4. Howarth NC, Saltzman E, Roberts SB: Dietary Fiber and Weight Regulation. Nutr. Rev. 2009; 59(5): 129–139. Publisher Full Text
5. Zou J, Chassaing B, Singh V, et al.: Fiber-Mediated Nourishment of Gut Microbiota Protects against Diet-Induced Obesity by Restoring IL-22-Mediated Colonic Health. Cell Host Microbe. 2018; 23(1): 41–53.e4. PubMed Abstract | Publisher Full Text | Free Full Text
6. Singh A, Singh SN: Dietary fiber content of Indian diets. Asian J. Pharm. Clin. Res. 2015; 58–61.
7. Puri S, Krishnaswamy S, Joshi S, et al.: Position of the Indian dietetic association: dietary fibre and health. [Review of Position of the Indian dietetic association: dietary fibre and health.]. Indian Dietetic Association. Indian Dietetic Association; 2018; pp. 1–7.
8. Ruhee RT: Dietary fiber and its effect on obesity: A review article. Adv. Med. Res. 2018; 01(01). Publisher Full Text
9. Snart J, Bibiloni R, Grayson T, et al.: Supplementation of the Diet with High-Viscosity Beta-Glucan Results in Enrichment for Lactobacilli in the Rat Cecum. Appl. Environ. Microbiol. 2006; 72(3): 1925–1931. PubMed Abstract | Publisher Full Text | Free Full Text
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12. Heaton KW: Food fibre as an obstacle to energy intake. Lancet. 1973; 302(7843): 1418–1421. PubMed Abstract | Publisher Full Text
13. Anderson JW, Baird P, Davis RH Jr, et al.: Health benefits of dietary fiber. Nutr. Rev. 2009; 67(4): 188–205. Publisher Full Text

Comments on this article Comments (0)

Version 1

VERSION 1 PUBLISHED 26 Apr 2024

Author details Author details

Suvarna Hebbar
Roles: Conceptualization, Funding Acquisition, Investigation, Resources, Validation, Writing – Original Draft Preparation, Writing – Review & Editing

Shashikiran Umakanth
Roles: Conceptualization, Methodology, Supervision, Validation, Writing – Review & Editing

Latha Thimmappa
Roles: Conceptualization, Formal Analysis, Methodology, Supervision, Validation, Writing – Review & Editing

Joniya Galbao
Roles: Conceptualization, Writing – Review & Editing

Competing interests

No competing interests were disclosed.

Grant information

This study is funded by IMCR-DHR (R.11014/12/2023-GIA/HR)
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Article Versions (1)

version 1

Published: 26 Apr 2024, 13:396

https://doi.org/10.12688/f1000research.147438.1

© 2024 Hebbar S et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Hebbar S, Umakanth S, Thimmappa L and Galbao J. Effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women: study protocol for a double-blinded randomized controlled trail. [version 1; peer review: 1 not approved]. F1000Research 2024, 13:396 (https://doi.org/10.12688/f1000research.147438.1)

NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.

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Open Peer Review

Version 1

VERSION 1

PUBLISHED 26 Apr 2024

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Reviewer Report 05 Feb 2025

Gary Frost, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, England, UK

Not Approved

https://doi.org/10.5256/f1000research.161634.r357073

I found the protocol somewhat confusing, primarily because the methods section combines both Phase 1 and Phase 2. It would be clearer if each phase were presented separately under distinct subheadings.

Including a schematic diagram of the intervention would greatly aid in understanding the different phases and how they are structured.

The rationale for expecting sex-specific differences in response to the dietary fiber intervention is unclear. Additionally, the purpose of the intervention itself needs to be better justified. Is this study specifically designed for women’s health? If so, the justification for conducting a single-sex study should be clearly articulated.

Some of the language used in the background section appears outdated and would benefit from revision. For example, terms like “roughage” should be updated to reflect current scientific terminology.

The study is described as stratified, randomized, controlled, and double-blind. However, given that the intervention involves dietary advice to achieve 40g of fiber intake compared to 20g, true double-blinding does not seem feasible. Clarification on how blinding is being implemented would be helpful. Additionally, why was a crossover design not considered, as it might have addressed some of these challenges?

There is confusion regarding the sample size. The power calculation suggests 90 participants per group, but the random allocation section mentions 60 per group. This discrepancy needs to be clarified.

The duration of the intervention is also difficult to determine. It appears to be 180 days for the intervention group, but this information is not presented clearly. Providing a concise summary of the study timeline would improve clarity.

There is limited justification for selecting a 20g difference in fiber intake between groups, as well as for the chosen length of the intervention. It would be useful to know if the research team has previously demonstrated success in increasing dietary fiber intake by 20g, as this can be challenging.

Relying solely on 24-hour dietary recalls to assess compliance is concerning, given the known limitations of this method. Are there any plans to include additional compliance measures?

Lastly, will the composition of dietary fiber (i.e., soluble vs. insoluble) be consistent across participants? The metabolic effects of these fiber types can vary significantly, and this should be addressed.

Is the rationale for, and objectives of, the study clearly described?

No
Is the study design appropriate for the research question?

Partly
Are sufficient details of the methods provided to allow replication by others?

No
Are the datasets clearly presented in a useable and accessible format?

No

Competing Interests: No competing interests were disclosed.

Reviewer Expertise: Nutrition and carbohydrate research

I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.

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Author Response 22 Mar 2025

Suvarna Hebbar, Clinical Nutrition and Dietetics, Manipal College of Health Professions, Manipal., 576104, India

22 Mar 2025

Author Response
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine ... Continue reading
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine the prevalence of insulin resistance.
Study Setting
This phase will be conducted in the Outpatient Departments (OPDs) of Medicine, Gynaecology, and Endocrinology at Kasturba Hospital, Manipal.
Sample Size & Selection

A total of 500 women will be screened to assess insulin resistance.

Participants will be categorized into two groups: overweight (BMI 23–24.9 kg/m²) and obese (BMI ≥ 25 kg/m²).

Each group will have at least 166 participants.

Inclusion Criteria

Women aged 35–55 years.

Willing to provide informed consent.

BMI ≥ 23 kg/m².

Exclusion Criteria

Women with conditions affecting nutritional status (e.g., tuberculosis, HIV, cancer, organ failure).

Women diagnosed with type 2 diabetes mellitus.

Individuals with hypertension, thyroid disorders, or any medical condition requiring medications affecting body weight (e.g., thyroxine, diuretics).

Pregnant or lactating women.

Women already on a weight-loss regime or consuming fiber above the recommended dietary allowance.

Women with contraindications for high fiber consumption (e.g., inflammatory bowel disease).

Data Collection Methods
Participants will undergo a baseline assessment, including:

Demographic Information: Age, education, occupation, income, marital history, place of residence, and family structure.

Anthropometric Measures: Height, weight, BMI, waist circumference, and hip circumference using standardized tools.

Biochemical Assessments:

Fasting blood glucose (hexokinase method).

HbA1c (TINA method).

Serum insulin (ECLIA).

Lipid profile (triglycerides, HDL, LDL, total cholesterol).

Dietary Assessment:

24-hour dietary recall and food frequency questionnaire analyzed using DietCal version 6.3.

Physical Activity Assessment:

Global Physical Activity Questionnaire (GPAQ).

Clinical Assessment: Evaluation of physical symptoms (e.g., bowel movement, satiety, leg pain, backache).

In-Depth Interviews

20 participants consuming low fiber (<20g/day) and 20 participants consuming moderate fiber (20-25g/day) will be interviewed telephonically for 45 minutes to assess barriers to fiber intake.

Phase 2: Randomized Controlled Trial (RCT)
Objective
To assess the impact of high dietary fiber intake (40g/day) on insulin resistance, body composition, and weight among overweight and obese women.
Study Design

Randomized, controlled trial.

Stratified Block Randomization (9 blocks of 20 participants each).

180 women will be randomized into:

Intervention Group (n=90): Receives 40g/day of fiber with dietary counselling.

Control Group (n=90): Receives 25g/day of fiber as part of a standard diet care plan.

Inclusion Criteria

Women from Phase 1 with abnormal HOMA-IR (>2), indicating insulin resistance.

Willing to adhere to a high-fiber diet if randomized to the intervention group.

Exclusion Criteria

Women unwilling to continue participation or adhere to the high-fiber diet.

Intervention & Control Groups
Intervention group
All women in the intervention arm will be counseled for about 15 minutes, and a customized diet chart consisting of high fiber of 40 grams will be provided. Nutritional empowerment on fiber shall be delivered to each woman enrolled. Necessary dietary advice on the modified diet plan and with a motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling, on the 15th day, women will be telephonically assessed on their 24-hour recall dietary intake. On the 30th day, the women will be contacted telephonically again to record their 24-hour recall of their dietary intake. Necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 60th day, the women will be again telephonically contacted to record their 24-hour recall on their dietary intake, and necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat is analyzed using body fat analyzer and a questionnaire on patient opinion regarding modified diet plan shall be ass. Necessaryessed as motivation and adherence towards fiber consumption subjects will be communicated telephonically on the 135th day. From the 136th to the 180th day, there shall not be any conversation regarding dietary modifications. On the 180th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data .24hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group.
Women in the control arm will get a traditional diet care plan with 25gm of fiber according to their health condition. Necessary dietary advice will be communicated to the control group on the first visit to the hospital. There shall be no telephonic communication with the control group till the 90th day. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hour dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer. On the 180th day, as a compliance-checking, the patient will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer

Data Analysis

Repeated Measures ANOVA will be used to evaluate changes in insulin resistance, body composition, and weight over time.

SPSS v16.0 will be used for statistical analysis.

Ethical Considerations

Approval obtained from the Institutional Research Committee and Institutional Ethics Committee (IEC).

Trial registered with the Clinical Trials Registry of India (CTRI/2022/01/039074).

Informed consent was obtained from all participants.

CONTROL ARM

Day 1

Traditional/standard care
(patient will be called to OPD)

Day 15
Nil

Day 30
Nil

Day 60
Nil

Day 90
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

INTERVENTION ARM

Day 1

Intervention
(patient will be called to OPD)

Customize the individual-specific diet plan
Nutritional counseling
Impart nutritional empowerment on fiber consumption
Handover of diet plan

Day 15

Reinforcement
(through telephone)

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 30

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 60

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 90

Outcome assessment
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Patient opinion on a modified diet
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135

Reinforcement (through telephone)

Motivation to follow a customized diet plan

Day 180

Checking compliance
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Compliance checklist
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135
Nil

Day180
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ

Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyser:
Visceral fat, S/C fat, muscle mass

3. Rationale for Sex-Specific Differences and Justification for a Single-Sex Study
This study is specifically designed for women’s health, as obesity and insulin resistance present distinct physiological and hormonal influences in females. The decision to focus on middle-aged women was based on prior evidence suggesting unique metabolic responses to dietary interventions in this demographic.
López, M. et al. (2016) - "Menopause, obesity, and insulin resistance: An emerging paradigm"

This study specifically explores the impact of menopause on metabolic health, highlighting the increased risk of insulin resistance and obesity in women as they transition through menopause. It aligns with your focus on middle-aged women and the unique metabolic responses they experience.

Reference: López, M. et al. "Menopause, obesity, and insulin resistance: An emerging paradigm." Endocrinology (2016).

Van Der Steeg, W. et al. (2010) - "Sex differences in insulin resistance in obesity"

This study investigates how hormonal factors, especially estrogen, affect insulin resistance and fat distribution differently in women, providing key insights into the sex-specific mechanisms that make middle-aged women particularly vulnerable to obesity and metabolic disorders.

Reference: Van Der Steeg, W. et al. "Sex differences in insulin resistance in obesity." Obesity Reviews (2010).

4. Updating Scientific Terminology in the Background Section
We appreciate the suggestion regarding outdated terminology. The term "roughage" and other obsolete language will be revised to align with current scientific terminology.
5. Clarification on Double-Blinding and Study Design
There was an error in the original study design description. This study is not a double-blind study but rather an open-ended study. This design was chosen to facilitate a deeper understanding of the real-world effects of dietary interventions on obesity and insulin resistance in middle-aged women, where factors like adherence to the intervention and participant feedback play an essential role in the analysis.

6. Sample Size Discrepancy
The final sample size of 180 participants (90 per group) was determined based on power calculations for insulin resistance and BMI, accounting for a 15% dropout rate. To ensure appropriate representation, participants were stratified based on the prevalence of obesity and overweight, maintaining a 2:1 ratio, with a higher proportion of obese individuals, as obesity is more prevalent in the target population.

7. Clarification of Study Duration
The total duration of the intervention is 180 days (6 months) for the intervention group, with structured follow-ups to ensure adherence and assess outcomes. Participants receive customized dietary counseling on Day 1, followed by reinforcement sessions via telephone on Days 15, 30, and 60 to monitor compliance and provide necessary modifications. Outcome assessments are conducted on Day 90 and Day 180, where anthropometric, biochemical, and dietary data are collected. A motivational follow-up is done on Day 135 to encourage continued adherence. The control group follows the same assessment schedule but does not receive interim dietary modifications. This structured timeline ensures a comprehensive evaluation of the intervention’s impact while maintaining participant engagement.

8. Justification for the 20g Fiber Difference and Study Duration
The 20g difference in fiber intake between groups was selected based on existing dietary recommendations and evidence supporting its impact on weight management and metabolic health. The intervention group receives 40g of fiber per 2000 kcal, aligning with the Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) guidelines. In contrast, the control group follows a standard 25g fiber intake. This difference ensures a meaningful contrast while remaining practical for adherence.
The 180-day (6-month) intervention period was chosen to allow sufficient time for stabilizing dietary habits and for metabolic changes, such as improvements in insulin resistance and body composition, to be observed. The feasibility of increasing dietary fiber intake by 20g has been supported by our preliminary observational study (2019), which assessed fiber intake and obesity among 564 women. This study highlighted a significant negative correlation between fiber intake and BMI, reinforcing the need for a structured dietary intervention to promote increased fiber consumption.

9. Addressing Compliance Assessment Concerns
Compliance assessment in this study is not solely based on 24-hour dietary recall; multiple tools are incorporated to ensure accuracy and reliability. In addition to the 24-hour recall and food frequency questionnaire, a compliance checklist is used to track adherence to the prescribed dietary plan. Furthermore, patient opinions on the modified diet are collected to assess acceptability and feasibility. Regular reinforcement sessions (via telephone on Days 15, 30, and 60) further help monitor compliance and address challenges.

10. Consistency in Fiber Composition (Soluble vs. Insoluble)
The study ensures consistency in dietary fiber composition across participants by providing a structured, customized diet plan that proportions soluble and insoluble fiber appropriately. The dietary sources primarily include whole grains, legumes, vegetables, and fruits, providing a balanced fiber mix. While the metabolic effects of soluble and insoluble fiber can vary, the intervention is designed to reflect a realistic, well-balanced dietary intake, aligning with established dietary guidelines. This approach ensures that all participants receive a comparable fiber composition, minimizing variability in metabolic responses while maintaining dietary feasibility.
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine the prevalence of insulin resistance.
Study Setting
This phase will be conducted in the Outpatient Departments (OPDs) of Medicine, Gynaecology, and Endocrinology at Kasturba Hospital, Manipal.
Sample Size & Selection

A total of 500 women will be screened to assess insulin resistance.

Participants will be categorized into two groups: overweight (BMI 23–24.9 kg/m²) and obese (BMI ≥ 25 kg/m²).

Each group will have at least 166 participants.

Inclusion Criteria

Women aged 35–55 years.

Willing to provide informed consent.

BMI ≥ 23 kg/m².

Exclusion Criteria

Women with conditions affecting nutritional status (e.g., tuberculosis, HIV, cancer, organ failure).

Women diagnosed with type 2 diabetes mellitus.

Individuals with hypertension, thyroid disorders, or any medical condition requiring medications affecting body weight (e.g., thyroxine, diuretics).

Pregnant or lactating women.

Women already on a weight-loss regime or consuming fiber above the recommended dietary allowance.

Women with contraindications for high fiber consumption (e.g., inflammatory bowel disease).

Data Collection Methods
Participants will undergo a baseline assessment, including:

Demographic Information: Age, education, occupation, income, marital history, place of residence, and family structure.

Anthropometric Measures: Height, weight, BMI, waist circumference, and hip circumference using standardized tools.

Biochemical Assessments:

Fasting blood glucose (hexokinase method).

HbA1c (TINA method).

Serum insulin (ECLIA).

Lipid profile (triglycerides, HDL, LDL, total cholesterol).

Dietary Assessment:

24-hour dietary recall and food frequency questionnaire analyzed using DietCal version 6.3.

Physical Activity Assessment:

Global Physical Activity Questionnaire (GPAQ).

Clinical Assessment: Evaluation of physical symptoms (e.g., bowel movement, satiety, leg pain, backache).

In-Depth Interviews

20 participants consuming low fiber (<20g/day) and 20 participants consuming moderate fiber (20-25g/day) will be interviewed telephonically for 45 minutes to assess barriers to fiber intake.

Phase 2: Randomized Controlled Trial (RCT)
Objective
To assess the impact of high dietary fiber intake (40g/day) on insulin resistance, body composition, and weight among overweight and obese women.
Study Design

Randomized, controlled trial.

Stratified Block Randomization (9 blocks of 20 participants each).

180 women will be randomized into:

Intervention Group (n=90): Receives 40g/day of fiber with dietary counselling.

Control Group (n=90): Receives 25g/day of fiber as part of a standard diet care plan.

Inclusion Criteria

Women from Phase 1 with abnormal HOMA-IR (>2), indicating insulin resistance.

Willing to adhere to a high-fiber diet if randomized to the intervention group.

Exclusion Criteria

Women unwilling to continue participation or adhere to the high-fiber diet.

Intervention & Control Groups
Intervention group
All women in the intervention arm will be counseled for about 15 minutes, and a customized diet chart consisting of high fiber of 40 grams will be provided. Nutritional empowerment on fiber shall be delivered to each woman enrolled. Necessary dietary advice on the modified diet plan and with a motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling, on the 15th day, women will be telephonically assessed on their 24-hour recall dietary intake. On the 30th day, the women will be contacted telephonically again to record their 24-hour recall of their dietary intake. Necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 60th day, the women will be again telephonically contacted to record their 24-hour recall on their dietary intake, and necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat is analyzed using body fat analyzer and a questionnaire on patient opinion regarding modified diet plan shall be ass. Necessaryessed as motivation and adherence towards fiber consumption subjects will be communicated telephonically on the 135th day. From the 136th to the 180th day, there shall not be any conversation regarding dietary modifications. On the 180th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data .24hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group.
Women in the control arm will get a traditional diet care plan with 25gm of fiber according to their health condition. Necessary dietary advice will be communicated to the control group on the first visit to the hospital. There shall be no telephonic communication with the control group till the 90th day. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hour dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer. On the 180th day, as a compliance-checking, the patient will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer

Data Analysis

Repeated Measures ANOVA will be used to evaluate changes in insulin resistance, body composition, and weight over time.

SPSS v16.0 will be used for statistical analysis.

Ethical Considerations

Approval obtained from the Institutional Research Committee and Institutional Ethics Committee (IEC).

Trial registered with the Clinical Trials Registry of India (CTRI/2022/01/039074).

Informed consent was obtained from all participants.

CONTROL ARM

Day 1

Traditional/standard care
(patient will be called to OPD)

Day 15
Nil

Day 30
Nil

Day 60
Nil

Day 90
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

INTERVENTION ARM

Day 1

Intervention
(patient will be called to OPD)

Customize the individual-specific diet plan
Nutritional counseling
Impart nutritional empowerment on fiber consumption
Handover of diet plan

Day 15

Reinforcement
(through telephone)

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 30

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 60

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 90

Outcome assessment
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Patient opinion on a modified diet
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135

Reinforcement (through telephone)

Motivation to follow a customized diet plan

Day 180

Checking compliance
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Compliance checklist
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135
Nil

Day180
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ

Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyser:
Visceral fat, S/C fat, muscle mass

3. Rationale for Sex-Specific Differences and Justification for a Single-Sex Study
This study is specifically designed for women’s health, as obesity and insulin resistance present distinct physiological and hormonal influences in females. The decision to focus on middle-aged women was based on prior evidence suggesting unique metabolic responses to dietary interventions in this demographic.
López, M. et al. (2016) - "Menopause, obesity, and insulin resistance: An emerging paradigm"

This study specifically explores the impact of menopause on metabolic health, highlighting the increased risk of insulin resistance and obesity in women as they transition through menopause. It aligns with your focus on middle-aged women and the unique metabolic responses they experience.

Reference: López, M. et al. "Menopause, obesity, and insulin resistance: An emerging paradigm." Endocrinology (2016).

Van Der Steeg, W. et al. (2010) - "Sex differences in insulin resistance in obesity"

This study investigates how hormonal factors, especially estrogen, affect insulin resistance and fat distribution differently in women, providing key insights into the sex-specific mechanisms that make middle-aged women particularly vulnerable to obesity and metabolic disorders.

Reference: Van Der Steeg, W. et al. "Sex differences in insulin resistance in obesity." Obesity Reviews (2010).

4. Updating Scientific Terminology in the Background Section
We appreciate the suggestion regarding outdated terminology. The term "roughage" and other obsolete language will be revised to align with current scientific terminology.
5. Clarification on Double-Blinding and Study Design
There was an error in the original study design description. This study is not a double-blind study but rather an open-ended study. This design was chosen to facilitate a deeper understanding of the real-world effects of dietary interventions on obesity and insulin resistance in middle-aged women, where factors like adherence to the intervention and participant feedback play an essential role in the analysis.

6. Sample Size Discrepancy
The final sample size of 180 participants (90 per group) was determined based on power calculations for insulin resistance and BMI, accounting for a 15% dropout rate. To ensure appropriate representation, participants were stratified based on the prevalence of obesity and overweight, maintaining a 2:1 ratio, with a higher proportion of obese individuals, as obesity is more prevalent in the target population.

7. Clarification of Study Duration
The total duration of the intervention is 180 days (6 months) for the intervention group, with structured follow-ups to ensure adherence and assess outcomes. Participants receive customized dietary counseling on Day 1, followed by reinforcement sessions via telephone on Days 15, 30, and 60 to monitor compliance and provide necessary modifications. Outcome assessments are conducted on Day 90 and Day 180, where anthropometric, biochemical, and dietary data are collected. A motivational follow-up is done on Day 135 to encourage continued adherence. The control group follows the same assessment schedule but does not receive interim dietary modifications. This structured timeline ensures a comprehensive evaluation of the intervention’s impact while maintaining participant engagement.

8. Justification for the 20g Fiber Difference and Study Duration
The 20g difference in fiber intake between groups was selected based on existing dietary recommendations and evidence supporting its impact on weight management and metabolic health. The intervention group receives 40g of fiber per 2000 kcal, aligning with the Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) guidelines. In contrast, the control group follows a standard 25g fiber intake. This difference ensures a meaningful contrast while remaining practical for adherence.
The 180-day (6-month) intervention period was chosen to allow sufficient time for stabilizing dietary habits and for metabolic changes, such as improvements in insulin resistance and body composition, to be observed. The feasibility of increasing dietary fiber intake by 20g has been supported by our preliminary observational study (2019), which assessed fiber intake and obesity among 564 women. This study highlighted a significant negative correlation between fiber intake and BMI, reinforcing the need for a structured dietary intervention to promote increased fiber consumption.

9. Addressing Compliance Assessment Concerns
Compliance assessment in this study is not solely based on 24-hour dietary recall; multiple tools are incorporated to ensure accuracy and reliability. In addition to the 24-hour recall and food frequency questionnaire, a compliance checklist is used to track adherence to the prescribed dietary plan. Furthermore, patient opinions on the modified diet are collected to assess acceptability and feasibility. Regular reinforcement sessions (via telephone on Days 15, 30, and 60) further help monitor compliance and address challenges.

10. Consistency in Fiber Composition (Soluble vs. Insoluble)
The study ensures consistency in dietary fiber composition across participants by providing a structured, customized diet plan that proportions soluble and insoluble fiber appropriately. The dietary sources primarily include whole grains, legumes, vegetables, and fruits, providing a balanced fiber mix. While the metabolic effects of soluble and insoluble fiber can vary, the intervention is designed to reflect a realistic, well-balanced dietary intake, aligning with established dietary guidelines. This approach ensures that all participants receive a comparable fiber composition, minimizing variability in metabolic responses while maintaining dietary feasibility.
Competing Interests: No competing interests were disclosed. Close
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Respond or Comment

COMMENTS ON THIS REPORT

Author Response 22 Mar 2025

Suvarna Hebbar, Clinical Nutrition and Dietetics, Manipal College of Health Professions, Manipal., 576104, India

22 Mar 2025

Author Response
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine ... Continue reading
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine the prevalence of insulin resistance.
Study Setting
This phase will be conducted in the Outpatient Departments (OPDs) of Medicine, Gynaecology, and Endocrinology at Kasturba Hospital, Manipal.
Sample Size & Selection

A total of 500 women will be screened to assess insulin resistance.

Participants will be categorized into two groups: overweight (BMI 23–24.9 kg/m²) and obese (BMI ≥ 25 kg/m²).

Each group will have at least 166 participants.

Inclusion Criteria

Women aged 35–55 years.

Willing to provide informed consent.

BMI ≥ 23 kg/m².

Exclusion Criteria

Women with conditions affecting nutritional status (e.g., tuberculosis, HIV, cancer, organ failure).

Women diagnosed with type 2 diabetes mellitus.

Individuals with hypertension, thyroid disorders, or any medical condition requiring medications affecting body weight (e.g., thyroxine, diuretics).

Pregnant or lactating women.

Women already on a weight-loss regime or consuming fiber above the recommended dietary allowance.

Women with contraindications for high fiber consumption (e.g., inflammatory bowel disease).

Data Collection Methods
Participants will undergo a baseline assessment, including:

Demographic Information: Age, education, occupation, income, marital history, place of residence, and family structure.

Anthropometric Measures: Height, weight, BMI, waist circumference, and hip circumference using standardized tools.

Biochemical Assessments:

Fasting blood glucose (hexokinase method).

HbA1c (TINA method).

Serum insulin (ECLIA).

Lipid profile (triglycerides, HDL, LDL, total cholesterol).

Dietary Assessment:

24-hour dietary recall and food frequency questionnaire analyzed using DietCal version 6.3.

Physical Activity Assessment:

Global Physical Activity Questionnaire (GPAQ).

Clinical Assessment: Evaluation of physical symptoms (e.g., bowel movement, satiety, leg pain, backache).

In-Depth Interviews

20 participants consuming low fiber (<20g/day) and 20 participants consuming moderate fiber (20-25g/day) will be interviewed telephonically for 45 minutes to assess barriers to fiber intake.

Phase 2: Randomized Controlled Trial (RCT)
Objective
To assess the impact of high dietary fiber intake (40g/day) on insulin resistance, body composition, and weight among overweight and obese women.
Study Design

Randomized, controlled trial.

Stratified Block Randomization (9 blocks of 20 participants each).

180 women will be randomized into:

Intervention Group (n=90): Receives 40g/day of fiber with dietary counselling.

Control Group (n=90): Receives 25g/day of fiber as part of a standard diet care plan.

Inclusion Criteria

Women from Phase 1 with abnormal HOMA-IR (>2), indicating insulin resistance.

Willing to adhere to a high-fiber diet if randomized to the intervention group.

Exclusion Criteria

Women unwilling to continue participation or adhere to the high-fiber diet.

Intervention & Control Groups
Intervention group
All women in the intervention arm will be counseled for about 15 minutes, and a customized diet chart consisting of high fiber of 40 grams will be provided. Nutritional empowerment on fiber shall be delivered to each woman enrolled. Necessary dietary advice on the modified diet plan and with a motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling, on the 15th day, women will be telephonically assessed on their 24-hour recall dietary intake. On the 30th day, the women will be contacted telephonically again to record their 24-hour recall of their dietary intake. Necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 60th day, the women will be again telephonically contacted to record their 24-hour recall on their dietary intake, and necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat is analyzed using body fat analyzer and a questionnaire on patient opinion regarding modified diet plan shall be ass. Necessaryessed as motivation and adherence towards fiber consumption subjects will be communicated telephonically on the 135th day. From the 136th to the 180th day, there shall not be any conversation regarding dietary modifications. On the 180th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data .24hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group.
Women in the control arm will get a traditional diet care plan with 25gm of fiber according to their health condition. Necessary dietary advice will be communicated to the control group on the first visit to the hospital. There shall be no telephonic communication with the control group till the 90th day. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hour dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer. On the 180th day, as a compliance-checking, the patient will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer

Data Analysis

Repeated Measures ANOVA will be used to evaluate changes in insulin resistance, body composition, and weight over time.

SPSS v16.0 will be used for statistical analysis.

Ethical Considerations

Approval obtained from the Institutional Research Committee and Institutional Ethics Committee (IEC).

Trial registered with the Clinical Trials Registry of India (CTRI/2022/01/039074).

Informed consent was obtained from all participants.

CONTROL ARM

Day 1

Traditional/standard care
(patient will be called to OPD)

Day 15
Nil

Day 30
Nil

Day 60
Nil

Day 90
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

INTERVENTION ARM

Day 1

Intervention
(patient will be called to OPD)

Customize the individual-specific diet plan
Nutritional counseling
Impart nutritional empowerment on fiber consumption
Handover of diet plan

Day 15

Reinforcement
(through telephone)

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 30

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 60

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 90

Outcome assessment
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Patient opinion on a modified diet
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135

Reinforcement (through telephone)

Motivation to follow a customized diet plan

Day 180

Checking compliance
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Compliance checklist
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135
Nil

Day180
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ

Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyser:
Visceral fat, S/C fat, muscle mass

3. Rationale for Sex-Specific Differences and Justification for a Single-Sex Study
This study is specifically designed for women’s health, as obesity and insulin resistance present distinct physiological and hormonal influences in females. The decision to focus on middle-aged women was based on prior evidence suggesting unique metabolic responses to dietary interventions in this demographic.
López, M. et al. (2016) - "Menopause, obesity, and insulin resistance: An emerging paradigm"

This study specifically explores the impact of menopause on metabolic health, highlighting the increased risk of insulin resistance and obesity in women as they transition through menopause. It aligns with your focus on middle-aged women and the unique metabolic responses they experience.

Reference: López, M. et al. "Menopause, obesity, and insulin resistance: An emerging paradigm." Endocrinology (2016).

Van Der Steeg, W. et al. (2010) - "Sex differences in insulin resistance in obesity"

This study investigates how hormonal factors, especially estrogen, affect insulin resistance and fat distribution differently in women, providing key insights into the sex-specific mechanisms that make middle-aged women particularly vulnerable to obesity and metabolic disorders.

Reference: Van Der Steeg, W. et al. "Sex differences in insulin resistance in obesity." Obesity Reviews (2010).

4. Updating Scientific Terminology in the Background Section
We appreciate the suggestion regarding outdated terminology. The term "roughage" and other obsolete language will be revised to align with current scientific terminology.
5. Clarification on Double-Blinding and Study Design
There was an error in the original study design description. This study is not a double-blind study but rather an open-ended study. This design was chosen to facilitate a deeper understanding of the real-world effects of dietary interventions on obesity and insulin resistance in middle-aged women, where factors like adherence to the intervention and participant feedback play an essential role in the analysis.

6. Sample Size Discrepancy
The final sample size of 180 participants (90 per group) was determined based on power calculations for insulin resistance and BMI, accounting for a 15% dropout rate. To ensure appropriate representation, participants were stratified based on the prevalence of obesity and overweight, maintaining a 2:1 ratio, with a higher proportion of obese individuals, as obesity is more prevalent in the target population.

7. Clarification of Study Duration
The total duration of the intervention is 180 days (6 months) for the intervention group, with structured follow-ups to ensure adherence and assess outcomes. Participants receive customized dietary counseling on Day 1, followed by reinforcement sessions via telephone on Days 15, 30, and 60 to monitor compliance and provide necessary modifications. Outcome assessments are conducted on Day 90 and Day 180, where anthropometric, biochemical, and dietary data are collected. A motivational follow-up is done on Day 135 to encourage continued adherence. The control group follows the same assessment schedule but does not receive interim dietary modifications. This structured timeline ensures a comprehensive evaluation of the intervention’s impact while maintaining participant engagement.

8. Justification for the 20g Fiber Difference and Study Duration
The 20g difference in fiber intake between groups was selected based on existing dietary recommendations and evidence supporting its impact on weight management and metabolic health. The intervention group receives 40g of fiber per 2000 kcal, aligning with the Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) guidelines. In contrast, the control group follows a standard 25g fiber intake. This difference ensures a meaningful contrast while remaining practical for adherence.
The 180-day (6-month) intervention period was chosen to allow sufficient time for stabilizing dietary habits and for metabolic changes, such as improvements in insulin resistance and body composition, to be observed. The feasibility of increasing dietary fiber intake by 20g has been supported by our preliminary observational study (2019), which assessed fiber intake and obesity among 564 women. This study highlighted a significant negative correlation between fiber intake and BMI, reinforcing the need for a structured dietary intervention to promote increased fiber consumption.

9. Addressing Compliance Assessment Concerns
Compliance assessment in this study is not solely based on 24-hour dietary recall; multiple tools are incorporated to ensure accuracy and reliability. In addition to the 24-hour recall and food frequency questionnaire, a compliance checklist is used to track adherence to the prescribed dietary plan. Furthermore, patient opinions on the modified diet are collected to assess acceptability and feasibility. Regular reinforcement sessions (via telephone on Days 15, 30, and 60) further help monitor compliance and address challenges.

10. Consistency in Fiber Composition (Soluble vs. Insoluble)
The study ensures consistency in dietary fiber composition across participants by providing a structured, customized diet plan that proportions soluble and insoluble fiber appropriately. The dietary sources primarily include whole grains, legumes, vegetables, and fruits, providing a balanced fiber mix. While the metabolic effects of soluble and insoluble fiber can vary, the intervention is designed to reflect a realistic, well-balanced dietary intake, aligning with established dietary guidelines. This approach ensures that all participants receive a comparable fiber composition, minimizing variability in metabolic responses while maintaining dietary feasibility.
1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine the prevalence of insulin resistance.
Study Setting
This phase will be conducted in the Outpatient Departments (OPDs) of Medicine, Gynaecology, and Endocrinology at Kasturba Hospital, Manipal.
Sample Size & Selection

A total of 500 women will be screened to assess insulin resistance.

Participants will be categorized into two groups: overweight (BMI 23–24.9 kg/m²) and obese (BMI ≥ 25 kg/m²).

Each group will have at least 166 participants.

Inclusion Criteria

Women aged 35–55 years.

Willing to provide informed consent.

BMI ≥ 23 kg/m².

Exclusion Criteria

Women with conditions affecting nutritional status (e.g., tuberculosis, HIV, cancer, organ failure).

Women diagnosed with type 2 diabetes mellitus.

Individuals with hypertension, thyroid disorders, or any medical condition requiring medications affecting body weight (e.g., thyroxine, diuretics).

Pregnant or lactating women.

Women already on a weight-loss regime or consuming fiber above the recommended dietary allowance.

Women with contraindications for high fiber consumption (e.g., inflammatory bowel disease).

Data Collection Methods
Participants will undergo a baseline assessment, including:

Demographic Information: Age, education, occupation, income, marital history, place of residence, and family structure.

Anthropometric Measures: Height, weight, BMI, waist circumference, and hip circumference using standardized tools.

Biochemical Assessments:

Fasting blood glucose (hexokinase method).

HbA1c (TINA method).

Serum insulin (ECLIA).

Lipid profile (triglycerides, HDL, LDL, total cholesterol).

Dietary Assessment:

24-hour dietary recall and food frequency questionnaire analyzed using DietCal version 6.3.

Physical Activity Assessment:

Global Physical Activity Questionnaire (GPAQ).

Clinical Assessment: Evaluation of physical symptoms (e.g., bowel movement, satiety, leg pain, backache).

In-Depth Interviews

20 participants consuming low fiber (<20g/day) and 20 participants consuming moderate fiber (20-25g/day) will be interviewed telephonically for 45 minutes to assess barriers to fiber intake.

Phase 2: Randomized Controlled Trial (RCT)
Objective
To assess the impact of high dietary fiber intake (40g/day) on insulin resistance, body composition, and weight among overweight and obese women.
Study Design

Randomized, controlled trial.

Stratified Block Randomization (9 blocks of 20 participants each).

180 women will be randomized into:

Intervention Group (n=90): Receives 40g/day of fiber with dietary counselling.

Control Group (n=90): Receives 25g/day of fiber as part of a standard diet care plan.

Inclusion Criteria

Women from Phase 1 with abnormal HOMA-IR (>2), indicating insulin resistance.

Willing to adhere to a high-fiber diet if randomized to the intervention group.

Exclusion Criteria

Women unwilling to continue participation or adhere to the high-fiber diet.

Intervention & Control Groups
Intervention group
All women in the intervention arm will be counseled for about 15 minutes, and a customized diet chart consisting of high fiber of 40 grams will be provided. Nutritional empowerment on fiber shall be delivered to each woman enrolled. Necessary dietary advice on the modified diet plan and with a motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling, on the 15th day, women will be telephonically assessed on their 24-hour recall dietary intake. On the 30th day, the women will be contacted telephonically again to record their 24-hour recall of their dietary intake. Necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 60th day, the women will be again telephonically contacted to record their 24-hour recall on their dietary intake, and necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat is analyzed using body fat analyzer and a questionnaire on patient opinion regarding modified diet plan shall be ass. Necessaryessed as motivation and adherence towards fiber consumption subjects will be communicated telephonically on the 135th day. From the 136th to the 180th day, there shall not be any conversation regarding dietary modifications. On the 180th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data .24hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group.
Women in the control arm will get a traditional diet care plan with 25gm of fiber according to their health condition. Necessary dietary advice will be communicated to the control group on the first visit to the hospital. There shall be no telephonic communication with the control group till the 90th day. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hour dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer. On the 180th day, as a compliance-checking, the patient will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer

Data Analysis

Repeated Measures ANOVA will be used to evaluate changes in insulin resistance, body composition, and weight over time.

SPSS v16.0 will be used for statistical analysis.

Ethical Considerations

Approval obtained from the Institutional Research Committee and Institutional Ethics Committee (IEC).

Trial registered with the Clinical Trials Registry of India (CTRI/2022/01/039074).

Informed consent was obtained from all participants.

CONTROL ARM

Day 1

Traditional/standard care
(patient will be called to OPD)

Day 15
Nil

Day 30
Nil

Day 60
Nil

Day 90
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

INTERVENTION ARM

Day 1

Intervention
(patient will be called to OPD)

Customize the individual-specific diet plan
Nutritional counseling
Impart nutritional empowerment on fiber consumption
Handover of diet plan

Day 15

Reinforcement
(through telephone)

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 30

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 60

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 90

Outcome assessment
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Patient opinion on a modified diet
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135

Reinforcement (through telephone)

Motivation to follow a customized diet plan

Day 180

Checking compliance
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Compliance checklist
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135
Nil

Day180
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ

Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyser:
Visceral fat, S/C fat, muscle mass

3. Rationale for Sex-Specific Differences and Justification for a Single-Sex Study
This study is specifically designed for women’s health, as obesity and insulin resistance present distinct physiological and hormonal influences in females. The decision to focus on middle-aged women was based on prior evidence suggesting unique metabolic responses to dietary interventions in this demographic.
López, M. et al. (2016) - "Menopause, obesity, and insulin resistance: An emerging paradigm"

This study specifically explores the impact of menopause on metabolic health, highlighting the increased risk of insulin resistance and obesity in women as they transition through menopause. It aligns with your focus on middle-aged women and the unique metabolic responses they experience.

Reference: López, M. et al. "Menopause, obesity, and insulin resistance: An emerging paradigm." Endocrinology (2016).

Van Der Steeg, W. et al. (2010) - "Sex differences in insulin resistance in obesity"

This study investigates how hormonal factors, especially estrogen, affect insulin resistance and fat distribution differently in women, providing key insights into the sex-specific mechanisms that make middle-aged women particularly vulnerable to obesity and metabolic disorders.

Reference: Van Der Steeg, W. et al. "Sex differences in insulin resistance in obesity." Obesity Reviews (2010).

4. Updating Scientific Terminology in the Background Section
We appreciate the suggestion regarding outdated terminology. The term "roughage" and other obsolete language will be revised to align with current scientific terminology.
5. Clarification on Double-Blinding and Study Design
There was an error in the original study design description. This study is not a double-blind study but rather an open-ended study. This design was chosen to facilitate a deeper understanding of the real-world effects of dietary interventions on obesity and insulin resistance in middle-aged women, where factors like adherence to the intervention and participant feedback play an essential role in the analysis.

6. Sample Size Discrepancy
The final sample size of 180 participants (90 per group) was determined based on power calculations for insulin resistance and BMI, accounting for a 15% dropout rate. To ensure appropriate representation, participants were stratified based on the prevalence of obesity and overweight, maintaining a 2:1 ratio, with a higher proportion of obese individuals, as obesity is more prevalent in the target population.

7. Clarification of Study Duration
The total duration of the intervention is 180 days (6 months) for the intervention group, with structured follow-ups to ensure adherence and assess outcomes. Participants receive customized dietary counseling on Day 1, followed by reinforcement sessions via telephone on Days 15, 30, and 60 to monitor compliance and provide necessary modifications. Outcome assessments are conducted on Day 90 and Day 180, where anthropometric, biochemical, and dietary data are collected. A motivational follow-up is done on Day 135 to encourage continued adherence. The control group follows the same assessment schedule but does not receive interim dietary modifications. This structured timeline ensures a comprehensive evaluation of the intervention’s impact while maintaining participant engagement.

8. Justification for the 20g Fiber Difference and Study Duration
The 20g difference in fiber intake between groups was selected based on existing dietary recommendations and evidence supporting its impact on weight management and metabolic health. The intervention group receives 40g of fiber per 2000 kcal, aligning with the Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) guidelines. In contrast, the control group follows a standard 25g fiber intake. This difference ensures a meaningful contrast while remaining practical for adherence.
The 180-day (6-month) intervention period was chosen to allow sufficient time for stabilizing dietary habits and for metabolic changes, such as improvements in insulin resistance and body composition, to be observed. The feasibility of increasing dietary fiber intake by 20g has been supported by our preliminary observational study (2019), which assessed fiber intake and obesity among 564 women. This study highlighted a significant negative correlation between fiber intake and BMI, reinforcing the need for a structured dietary intervention to promote increased fiber consumption.

9. Addressing Compliance Assessment Concerns
Compliance assessment in this study is not solely based on 24-hour dietary recall; multiple tools are incorporated to ensure accuracy and reliability. In addition to the 24-hour recall and food frequency questionnaire, a compliance checklist is used to track adherence to the prescribed dietary plan. Furthermore, patient opinions on the modified diet are collected to assess acceptability and feasibility. Regular reinforcement sessions (via telephone on Days 15, 30, and 60) further help monitor compliance and address challenges.

10. Consistency in Fiber Composition (Soluble vs. Insoluble)
The study ensures consistency in dietary fiber composition across participants by providing a structured, customized diet plan that proportions soluble and insoluble fiber appropriately. The dietary sources primarily include whole grains, legumes, vegetables, and fruits, providing a balanced fiber mix. While the metabolic effects of soluble and insoluble fiber can vary, the intervention is designed to reflect a realistic, well-balanced dietary intake, aligning with established dietary guidelines. This approach ensures that all participants receive a comparable fiber composition, minimizing variability in metabolic responses while maintaining dietary feasibility.
Competing Interests: No competing interests were disclosed. Close
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Version 1 26 Apr 24	read

Gary Frost, Imperial College London, London, UK

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Reviewer Report

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05 Feb 2025 | for Version 1

Gary Frost, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, England, UK

11 Views Cite this report Responses(1)

Not Approved

Is the rationale for, and objectives of, the study clearly described?

No
Is the study design appropriate for the research question?

Partly
Are sufficient details of the methods provided to allow replication by others?

No
Are the datasets clearly presented in a useable and accessible format?

No

Competing Interests

No competing interests were disclosed.

Reviewer Expertise

Nutrition and carbohydrate research

Respond to this report

Responses (1)

Author Response

22 Mar 2025

Suvarna Hebbar, Clinical Nutrition and Dietetics, Manipal College of Health Professions, Manipal., 576104, India

1. Clarity in Methods Section (Phase 1 & Phase 2 Separation)
Phase 1
Objective
The primary aim of Phase 1 is to screen middle-aged overweight and obese women to determine the prevalence of insulin resistance.
Study Setting
This phase will be conducted in the Outpatient Departments (OPDs) of Medicine, Gynaecology, and Endocrinology at Kasturba Hospital, Manipal.
Sample Size & Selection

A total of 500 women will be screened to assess insulin resistance.
Participants will be categorized into two groups: overweight (BMI 23–24.9 kg/m²) and obese (BMI ≥ 25 kg/m²).
Each group will have at least 166 participants.

Inclusion Criteria

Women aged 35–55 years.
Willing to provide informed consent.
BMI ≥ 23 kg/m².

Exclusion Criteria

Women with conditions affecting nutritional status (e.g., tuberculosis, HIV, cancer, organ failure).
Women diagnosed with type 2 diabetes mellitus.
Individuals with hypertension, thyroid disorders, or any medical condition requiring medications affecting body weight (e.g., thyroxine, diuretics).
Pregnant or lactating women.
Women already on a weight-loss regime or consuming fiber above the recommended dietary allowance.
Women with contraindications for high fiber consumption (e.g., inflammatory bowel disease).

Data Collection Methods
Participants will undergo a baseline assessment, including:

Demographic Information: Age, education, occupation, income, marital history, place of residence, and family structure.
Anthropometric Measures: Height, weight, BMI, waist circumference, and hip circumference using standardized tools.
Biochemical Assessments:
- Fasting blood glucose (hexokinase method).
- HbA1c (TINA method).
- Serum insulin (ECLIA).
- Lipid profile (triglycerides, HDL, LDL, total cholesterol).
Dietary Assessment:
- 24-hour dietary recall and food frequency questionnaire analyzed using DietCal version 6.3.
Physical Activity Assessment:
- Global Physical Activity Questionnaire (GPAQ).
Clinical Assessment: Evaluation of physical symptoms (e.g., bowel movement, satiety, leg pain, backache).

In-Depth Interviews

20 participants consuming low fiber (<20g/day) and 20 participants consuming moderate fiber (20-25g/day) will be interviewed telephonically for 45 minutes to assess barriers to fiber intake.

Phase 2: Randomized Controlled Trial (RCT)
Objective
To assess the impact of high dietary fiber intake (40g/day) on insulin resistance, body composition, and weight among overweight and obese women.
Study Design

Randomized, controlled trial.
Stratified Block Randomization (9 blocks of 20 participants each).
180 women will be randomized into:
- Intervention Group (n=90): Receives 40g/day of fiber with dietary counselling.
- Control Group (n=90): Receives 25g/day of fiber as part of a standard diet care plan.

Inclusion Criteria

Women from Phase 1 with abnormal HOMA-IR (>2), indicating insulin resistance.
Willing to adhere to a high-fiber diet if randomized to the intervention group.

Exclusion Criteria

Women unwilling to continue participation or adhere to the high-fiber diet.

Intervention & Control Groups
Intervention group
All women in the intervention arm will be counseled for about 15 minutes, and a customized diet chart consisting of high fiber of 40 grams will be provided. Nutritional empowerment on fiber shall be delivered to each woman enrolled. Necessary dietary advice on the modified diet plan and with a motivation to adhere to the diet plan will be communicated only to the intervention group. After the first counselling, on the 15th day, women will be telephonically assessed on their 24-hour recall dietary intake. On the 30th day, the women will be contacted telephonically again to record their 24-hour recall of their dietary intake. Necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 60th day, the women will be again telephonically contacted to record their 24-hour recall on their dietary intake, and necessary dietary changes on the modified diet plan will be advised, and motivation to adhere to the diet plan will be continued. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat is analyzed using body fat analyzer and a questionnaire on patient opinion regarding modified diet plan shall be ass. Necessaryessed as motivation and adherence towards fiber consumption subjects will be communicated telephonically on the 135th day. From the 136th to the 180th day, there shall not be any conversation regarding dietary modifications. On the 180th day, as a compliance-checking, the women will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data .24hr dietary recall, food frequency analyzed using DietCal version 6.3., physical activity data assessed by using GPAQ, body fat analyzed using body fat analyzer and diet compliance on the modified diet plan shall be assessed.

Control group.
Women in the control arm will get a traditional diet care plan with 25gm of fiber according to their health condition. Necessary dietary advice will be communicated to the control group on the first visit to the hospital. There shall be no telephonic communication with the control group till the 90th day. On the 90th day, as an outcome-based assessment, women will be called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hour dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer. On the 180th day, as a compliance-checking, the patient will be again called to the hospital for the anthropometric data, biochemical data followed by dietary data, a 24-hr dietary recall, food frequency analyzed using DietCal version 6.3, physical activity data assessed by using GPAQ, and body fat is analyzed using body fat analyzer

Data Analysis

Repeated Measures ANOVA will be used to evaluate changes in insulin resistance, body composition, and weight over time.
SPSS v16.0 will be used for statistical analysis.

Ethical Considerations

Approval obtained from the Institutional Research Committee and Institutional Ethics Committee (IEC).
Trial registered with the Clinical Trials Registry of India (CTRI/2022/01/039074).
Informed consent was obtained from all participants.

CONTROL ARM

Day 1

Traditional/standard care
(patient will be called to OPD)

Day 15
Nil

Day 30
Nil

Day 60
Nil

Day 90
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

INTERVENTION ARM

Day 1

Intervention
(patient will be called to OPD)

Customize the individual-specific diet plan
Nutritional counseling
Impart nutritional empowerment on fiber consumption
Handover of diet plan

Day 15

Reinforcement
(through telephone)

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 30

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 60

Tool 2: 24hr recall
Tool 3: GPAQ
Modification of diet plan (if required)
Motivate to adhere to the intervention

Day 90

Outcome assessment
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Patient opinion on a modified diet
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135

Reinforcement (through telephone)

Motivation to follow a customized diet plan

Day 180

Checking compliance
(patient will be called to OPD)
Basic data:
Tool 2: 24-hour recall and food frequency
Tool 3: GPAQ
Tool 4: Clinical assessment scale
Tool 5: Compliance checklist
Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyzer:
Visceral fat, S/C fat, muscle mass

Day 135
Nil

Day180
(patient will be called to OPD)
Basic data:
Tool 2: 24hr recall and food frequency
Tool 3: GPAQ

Biochemical parameters:
FBS, HbA1c, Sr. Insulin and lipid profile
Body fat analyser:
Visceral fat, S/C fat, muscle mass

3. Rationale for Sex-Specific Differences and Justification for a Single-Sex Study
This study is specifically designed for women’s health, as obesity and insulin resistance present distinct physiological and hormonal influences in females. The decision to focus on middle-aged women was based on prior evidence suggesting unique metabolic responses to dietary interventions in this demographic.
López, M. et al. (2016) - "Menopause, obesity, and insulin resistance: An emerging paradigm"

This study specifically explores the impact of menopause on metabolic health, highlighting the increased risk of insulin resistance and obesity in women as they transition through menopause. It aligns with your focus on middle-aged women and the unique metabolic responses they experience.
Reference: López, M. et al. "Menopause, obesity, and insulin resistance: An emerging paradigm." Endocrinology (2016).

Van Der Steeg, W. et al. (2010) - "Sex differences in insulin resistance in obesity"

This study investigates how hormonal factors, especially estrogen, affect insulin resistance and fat distribution differently in women, providing key insights into the sex-specific mechanisms that make middle-aged women particularly vulnerable to obesity and metabolic disorders.
Reference: Van Der Steeg, W. et al. "Sex differences in insulin resistance in obesity." Obesity Reviews (2010).

4. Updating Scientific Terminology in the Background Section
We appreciate the suggestion regarding outdated terminology. The term "roughage" and other obsolete language will be revised to align with current scientific terminology.
5. Clarification on Double-Blinding and Study Design
There was an error in the original study design description. This study is not a double-blind study but rather an open-ended study. This design was chosen to facilitate a deeper understanding of the real-world effects of dietary interventions on obesity and insulin resistance in middle-aged women, where factors like adherence to the intervention and participant feedback play an essential role in the analysis.

6. Sample Size Discrepancy
The final sample size of 180 participants (90 per group) was determined based on power calculations for insulin resistance and BMI, accounting for a 15% dropout rate. To ensure appropriate representation, participants were stratified based on the prevalence of obesity and overweight, maintaining a 2:1 ratio, with a higher proportion of obese individuals, as obesity is more prevalent in the target population.

7. Clarification of Study Duration
The total duration of the intervention is 180 days (6 months) for the intervention group, with structured follow-ups to ensure adherence and assess outcomes. Participants receive customized dietary counseling on Day 1, followed by reinforcement sessions via telephone on Days 15, 30, and 60 to monitor compliance and provide necessary modifications. Outcome assessments are conducted on Day 90 and Day 180, where anthropometric, biochemical, and dietary data are collected. A motivational follow-up is done on Day 135 to encourage continued adherence. The control group follows the same assessment schedule but does not receive interim dietary modifications. This structured timeline ensures a comprehensive evaluation of the intervention’s impact while maintaining participant engagement.

8. Justification for the 20g Fiber Difference and Study Duration
The 20g difference in fiber intake between groups was selected based on existing dietary recommendations and evidence supporting its impact on weight management and metabolic health. The intervention group receives 40g of fiber per 2000 kcal, aligning with the Indian Council of Medical Research (ICMR) and National Institute of Nutrition (NIN) guidelines. In contrast, the control group follows a standard 25g fiber intake. This difference ensures a meaningful contrast while remaining practical for adherence.
The 180-day (6-month) intervention period was chosen to allow sufficient time for stabilizing dietary habits and for metabolic changes, such as improvements in insulin resistance and body composition, to be observed. The feasibility of increasing dietary fiber intake by 20g has been supported by our preliminary observational study (2019), which assessed fiber intake and obesity among 564 women. This study highlighted a significant negative correlation between fiber intake and BMI, reinforcing the need for a structured dietary intervention to promote increased fiber consumption.

9. Addressing Compliance Assessment Concerns
Compliance assessment in this study is not solely based on 24-hour dietary recall; multiple tools are incorporated to ensure accuracy and reliability. In addition to the 24-hour recall and food frequency questionnaire, a compliance checklist is used to track adherence to the prescribed dietary plan. Furthermore, patient opinions on the modified diet are collected to assess acceptability and feasibility. Regular reinforcement sessions (via telephone on Days 15, 30, and 60) further help monitor compliance and address challenges.

10. Consistency in Fiber Composition (Soluble vs. Insoluble)
The study ensures consistency in dietary fiber composition across participants by providing a structured, customized diet plan that proportions soluble and insoluble fiber appropriately. The dietary sources primarily include whole grains, legumes, vegetables, and fruits, providing a balanced fiber mix. While the metabolic effects of soluble and insoluble fiber can vary, the intervention is designed to reflect a realistic, well-balanced dietary intake, aligning with established dietary guidelines. This approach ensures that all participants receive a comparable fiber composition, minimizing variability in metabolic responses while maintaining dietary feasibility.

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Competing Interests

No competing interests were disclosed.

Alongside their report, reviewers assign a status to the article:

Approved - the paper is scientifically sound in its current form and only minor, if any, improvements are suggested

Approved with reservations - A number of small changes, sometimes more significant revisions are required to address specific details and improve the papers academic merit.

Not approved - fundamental flaws in the paper seriously undermine the findings and conclusions

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Effect of high dietary fiber intake on insulin resistance, body composition and weight, among overweight or obese middle-aged women: study protocol for a double-blinded randomized controlled trail.

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