A New Approach Using BMI and FMI as Predictors of Cardio-Vascular Risk Factors among Mexican Young Adults

Round 1

Reviewer 1 Report

The study explored the prediction abilities of several obesity-related indicators for CVD risk factors. The study design is sound and it is of significant public health values.

A few suggestions:

1. Is a two-sided P value of 0.05 used to determine statistical significance?

2. In table 1, the digits retained were inconsistent. Please make them consistent.

Author Response

Comments and Suggestions for Authors:

The study explored the prediction abilities of several obesity-related indicators for CVD risk factors. The study design is sound and it is of significant public health values.

A few suggestions:

Comments 1: Is a two-sided P value of 0.05 used to determine statistical significance?

Response 1: Yes, it is. Statistical significance was set at two-sided p < 0.05. This information was included in the Material and Methods section (Pg. 3).

 

Comments 2: In Table 1, the digits retained were inconsistent. Please make them consistent.

Response 2: The mistake was corrected (Pg. 8).

 

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

General Comments:

1. Introduction and Background: The manuscript provides a comprehensive overview of the current understanding of BMI, adiposity, and their implications in cardiovascular risk factors (CVRFs). The emphasis on the discrepancies in cut-off values across different populations is particularly relevant and timely.
2. Methodological Rigor: The cross-sectional design is a limitation, as causality cannot be inferred. Future studies should consider a longitudinal approach to track changes over time and establish causality.

Specific Comments:

 

1. Cut-off Points: The manuscript highlights the discrepancies in cut-off values for BMI, WC, BF%, and FMI across different populations. It would be beneficial to delve deeper into the reasons behind these discrepancies. Are they purely genetic, or do environmental factors, diet, and lifestyle play a role?
2. Comparison with Other Populations: While the study does a commendable job comparing Mexican young adults with other populations, it might be beneficial to include more diverse populations for a comprehensive understanding.
3. Race-specific Characteristics: The manuscript touches upon the race-specific characteristics of body composition. It would be insightful to explore how socio-economic factors, cultural practices, and dietary habits influence these characteristics within the Mexican population.
4. Abdominal Obesity: The emphasis on WC as a predictor of CVRFs is well-placed. However, the manuscript could benefit from a discussion on the physiological mechanisms linking WC and cardiovascular risks, especially in the context of the Mexican population.
5. Muscle Metabolism: The section on muscle metabolism and its disruption due to obesity is intriguing. It would be beneficial to explore the implications of these disruptions in the context of physical activity, exercise regimens, and potential interventions.
6. Statistical Analysis: While the manuscript mentions the use of regression models, it would be helpful to provide more details on the statistical tests used, the assumptions checked, and any potential confounders adjusted for.
7. Clinical Implications: The manuscript could further emphasize the clinical implications of the findings. How can clinicians use this information in practice? Are there any recommendations for revising current guidelines based on the study's findings?
8. Future Directions: The conclusion briefly touches upon the need for future studies. It would be beneficial to provide more specific directions. For instance, would a study focusing on dietary habits and physical activity in the context of BMI and adiposity be beneficial?
9. Figures and Tables: Consider including more visual representations, such as graphs or charts, to illustrate the discrepancies in cut-off values across different populations and the associated CVRFs.
10. Language and Clarity: The manuscript is well-written, but there are a few sections where the language could be simplified for better clarity, especially for readers who might not be experts in the field.

Author Response

General Comments:

Introduction and Background: The manuscript provides a comprehensive overview of the current understanding of BMI, adiposity, and their implications in cardiovascular risk factors (CVRFs). The emphasis on the discrepancies in cut-off values across different populations is particularly relevant and timely.

Methodological Rigor: The cross-sectional design is a limitation, as causality cannot be inferred. Future studies should consider a longitudinal approach to track changes over time and establish causality.

This information was included in the Discussion section (Pg. 15).

Specific Comments:

Comments 1: Cut-off Points: The manuscript highlights the discrepancies in cut-off values for BMI, WC, BF%, and FMI across different populations. It would be beneficial to delve deeper into the reasons behind these discrepancies. Are they purely genetic, or do environmental factors, diet, and lifestyle play a role?

Response 1: Optimal cut-off values vary across different ethnicities due to different factors. First, it has been observed that cut-off values linearly increase with increasing population means. On the other hand, genetic differences play a major role in determining changes in body composition and metabolism in addition to an array of risk factors due to distinct social and environmental factors, such as diet, physical activity, and lifestyle, as well as socioeconomic and demographic status.

This information was included in the Discussion section (Pg. 13).

Comments 2: Comparison with Other Populations: While the study does a commendable job comparing Mexican young adults with other populations, it might be beneficial to include more diverse populations for a comprehensive understanding.

Response 2: We included a more diverse population such as Mexican, Japanese, Chinese, Brazilian, Colombian, Polish Caucasian, and Portuguese, expecting a more comprehensive understanding.

This information was included in the Discussion section (Pg. 11,12).

Comments 3: Race-specific Characteristics: The manuscript touches upon the race-specific characteristics of body composition. It would be insightful to explore how socio-economic factors, cultural practices, and dietary habits influence these characteristics within the Mexican population.

Response 3: In Mexico, the growth of national income, the increasing urbanization, and the globalization of food production have promoted unhealthy food choices and disincentives to engage in physical activity leading to a positive energy balance which underlies the increase in the prevalence of overweight and obesity, and negative changes in body composition related to non-communicable disease, such as CVRFs.

This information was included in the Discussion section (Pg. 13).

Comments 4: Abdominal Obesity: The emphasis on WC as a predictor of CVRFs is well-placed. However, the manuscript could benefit from a discussion on the physiological mechanisms linking WC and cardiovascular risks, especially in the context of the Mexican population.

Response 4: Chronic exposure to a positive net caloric intake increased genetic predisposition, and sedentary lifestyles are significant contributors to abdominal obesity and dyslipidemias in Mexico. It has been established that abdominal obesity, assessed by WC (≥94 and ≥80 cm for males and women, respectively), is a strong predictor of CVRFs like high TG, among different populations like Mexican, Peruvian, Canadian, Brazilian, and American. The most significant contributing factor for obesity-related dyslipidemia is likely uncontrolled fatty acid release from adipose tissue, especially visceral adipose tissue, through lipolysis, which causes increased delivery of fatty acids to the liver and synthesis of very-low-density lipoprotein (VLDL). Increased levels of free fatty acids can decrease mRNA expression or activity of lipoprotein lipase (LPL) in adipose tissue and skeletal muscle, and increased synthesis of VLDL in the liver can inhibit lipolysis of chylomicrons, which promotes hypertriglyceridemia.

This information was updated in the Discussion section (Pg.13).

Comments 5: Muscle Metabolism: The section on muscle metabolism and its disruption due to obesity is intriguing. It would be beneficial to explore the implications of these disruptions in the context of physical activity, exercise regimens, and potential interventions.

Response 5: The loss of muscle mass is an undesirable inherent consequence of physical inactivity. Thus, intervention programs that increase levels of physical activity should have protective effects. A regular exercise program (3 times/week) that includes resistance and endurance exercise training would have a major positive effect on improving muscle mass, strength, and function.

In response to contracting muscle, skeletal muscle cells express and secrete many myokines, such as IL-6, IL-8, IL-15, fibroblast growth factor 21, irisin, myonectin, and myostatin. They offset the deleterious effects of inflammatory cytokines and subsequently, have beneficial effects on glucose and lipid metabolism as well as inflammation.

This information was included in the Discussion section (Pg.14).

Comments 6: Statistical Analysis: While the manuscript mentions the use of regression models, it would be helpful to provide more details on the statistical tests used, the assumptions checked, and any potential confounders adjusted for.

Response 6: Multiple logistic regression analyses were performed to estimate odds ratios (ORs) with 95% confidence intervals (95%CI) of anthropometric and body composition measures as independent variables for the presence of CVRFs, as the dependent variable. Three models were fitted for each measurement by three cut-off points: Model 1 in agreement with the cut-off points from current guidelines for WC (≥80 cm in women and ≥94 cm in men), BF% (≥35% in women and ≥25% in men), BMI (≥25 kg/m2 in both gender), FMI (≥8.2 kg/m2 in women and ≥5.2 kg/m2 in men) and FFMI (≤15 kg/m2 in women and ≤17 kg/m2 in men) [12–14], model 2 consistent with the 50th percentile cut-off points, and model 3 according to the average of optimal cut-off points determined by Youden index from ROC curves. All models were adjusted by age.

This information was included in the Material and Methods section (Pg.3).

Comments 7: Clinical Implications: The manuscript could further emphasize the clinical implications of the findings. How can clinicians use this information in practice? Are there any recommendations for revising current guidelines based on the study's findings?

Response 7: Both BMI and FMI, easily obtainable and interpretable anthropometric measures, should be included as important tools for the screening of CVRFs among Mexican young adults in clinical practice, and health personnel should apply more appropriate thresholds of these body composition measures, that the currently recommended. This information was included in the Conclusion section (Pg.15).

Our study provides the need for revising current guidelines and considering developing new evidence-based cut-off points to improve the definition of obesity among Mexican young adults that can be able to identify those with the greatest risks of CVRFs. This information was included in the Discussion section (Pg. 15).

Comments 8: Future Directions: The conclusion briefly touches upon the need for future studies. It would be beneficial to provide more specific directions. For instance, would a study focusing on dietary habits and physical activity in the context of BMI and adiposity be beneficial?

Response 8: Future studies should consider a longitudinal approach to track changes over time and establish causality. Besides, prospective studies examining the incidence of CVRFs according to our proposed cut-off points are needed to further ascertain the accuracy of our obesity definition in classifying CVRFs. In addition, future studies examining changes in fat and muscle mass will provide further insight into body composition and its participation in a pro-inflammatory state related to the presence of CVRFs. Future studies may need to consider lifestyle factors, such as physical activity and dietary habits, to provide more information about their contribution to the variation of optimal cut-off values.

This information was updated in the Discussion section (Pg. 15).

Comments 9: Figures and Tables: Consider including more visual representations, such as graphs or charts, to illustrate the discrepancies in cut-off values across different populations and the associated CVRFs.

Response 9: Table 6 illustrates the discrepancies in cut-off values of anthropometric and body composition measures and the associated CVRFs across different populations.

This was included in the Discussion section (Pg. 12).

Comments 10: Language and Clarity: The manuscript is well-written, but there are a few sections where the language could be simplified for better clarity, especially for readers who might not be experts in the field.

Response 10: This was considered. The language in different sections of the manuscript was simplified, expecting it to be more understandable.

 

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have sufficiently answered my concerns. I recommend this work for publication.

Author Response

Comments and Suggestions for Authors

The authors have sufficiently answered my concerns. I recommend this work for publication.

 

Response: We highly appreciate your valuable comment.

 

Please see the attachment