Anthropometric and Body Composition Changes After Bariatric Surgery—The Effect of Sex, Age, and Type of Surgery

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

I read the manuscript by Soares Guerra on changes in anthropometric and body composition measures after bariatric surgery with great interest. I appreciate the authors' efforts to conduct a scientifically sound and technically rigorous study.

However, the most significant limitation is the small sample size. This is evident in the paradoxical mean values for preoperative and postoperative intervals, which are lower than the standard deviation—a strong indication of high variance or the presence of outliers. These outliers may have disproportionately affected the mean values. I recommend examining the data distribution and using medians instead of means if the data is skewed.

Another key issue is the lack of patient-first language. Instead of "obese people," the preferred term is "people living with obesity." Additionally, obesity has been recognized as a disease in its own right by the American Medical Association (2013) rather than merely a risk factor for other conditions. However, the first sentences of the Introduction suggest otherwise. Similarly, the term "obesity-related health problems" is preferable to "comorbidities." For further guidance, I recommend referring to IFSO’s recommended terminology.

The tables, while informative, are somewhat difficult to follow. I suggest aggregating the key results into a single comprehensive table and including relevant diagrams for clarity. The extensive tables could be provided as supplementary material instead.

In the Discussion, I recommend shifting the focus from merely reiterating the results to a deeper interpretation of findings in relation to existing literature. Rather than contrasting study designs, the emphasis should be on how these findings contribute to or challenge current knowledge in the field.

Overall, this study addresses an important topic and provides valuable insights into body composition changes after bariatric surgery. Addressing the small sample size, improving data presentation, and adopting patient-first language will enhance the manuscript’s clarity, accuracy, and impact. Additionally, refining the Discussion to focus on interpretation rather than description will strengthen its contribution to the field. I appreciate the authors' efforts and look forward to seeing a revised version that incorporates these improvements.

Comments on the Quality of English Language

As mentioned earlier, the use of patient-first language and IFSO-approved terminology is recommended.

Author Response

The authors acknowledge this important appreciation of the manuscript and express recognition for the useful comments and all the suggestions.

 

Reviewer 1

I read the manuscript by Soares Guerra on changes in anthropometric and body composition measures after bariatric surgery with great interest. I appreciate the authors' efforts to conduct a scientifically sound and technically rigorous study.

 

R: Thank you very much.

 

However, the most significant limitation is the small sample size. This is evident in the paradoxical mean values for preoperative and postoperative intervals, which are lower than the standard deviation—a strong indication of high variance or the presence of outliers. These outliers may have disproportionately affected the mean values.

 

R: We authors recognize the limitation regarding the low sample size. However, it reflects the demand for the surgical treatment of obesity in a private hospital. The sentence: “Moreover, the low sample size may have hampered the detection of differences in the anthropometric characteristics of the participants, between sexes, age classes and type of surgery.”

Was changed to better reflect this issue:

“Moreover, the low sample size is an important limitation. It may have hampered the detection of differences in the anthropometric characteristics of the participants, between sexes, age classes and type of surgery. Also, the study would benefit from applying regression analysis to account for all these factors in a single model, instead of showing the stratifications according to sex, age categories and type of surgery. However, our low sample size did not allow us to conduct a regression analysis. Moreover, this sample may not reflect the anthropometric and body composition, and other individual and lifestyle characteristics of patients eligible for surgery. However, all eligible patients who underwent metabolic and bariatric surgery at a Multidisciplinary Obesity Treatment Unit of a private Hospital during the study timeline (approximately 5 years) are part of the sample. So this number (57 participants) reflects our reality in terms of surgical treatment of obesity.”

 

I recommend examining the data distribution and using medians instead of means if the data is skewed.

 

R: The normality of the variable’s distribution was tested using Kolmogorov‑Smirnov test. This information was missing from methodology in the original manuscript and is now added:

“Data was tested for normal distribution using the Kolmogorov‑Smirnov test.”

 

Another key issue is the lack of patient-first language. Instead of "obese people," the preferred term is "people living with obesity." Additionally, obesity has been recognized as a disease in its own right by the American Medical Association (2013) rather than merely a risk factor for other conditions. However, the first sentences of the Introduction suggest otherwise. Similarly, the term "obesity-related health problems" is preferable to "comorbidities." For further guidance, I recommend referring to IFSO’s recommended terminology.

 

R: This recommendation was followed, and the language was changed accordingly throughout the manuscript text.

 

The tables, while informative, are somewhat difficult to follow. I suggest aggregating the key results into a single comprehensive table and including relevant diagrams for clarity. The extensive tables could be provided as supplementary material instead.

 

R: The tables were restructured in order to provide clarity.

 

In the Discussion, I recommend shifting the focus from merely reiterating the results to a deeper interpretation of findings in relation to existing literature. Rather than contrasting study designs, the emphasis should be on how these findings contribute to or challenge current knowledge in the field.

 

R: Accordingly, Discussion was rewritten.

 

Overall, this study addresses an important topic and provides valuable insights into body composition changes after bariatric surgery. Addressing the small sample size, improving data presentation, and adopting patient-first language will enhance the manuscript’s clarity, accuracy, and impact. Additionally, refining the Discussion to focus on interpretation rather than description will strengthen its contribution to the field. I appreciate the authors' efforts and look forward to seeing a revised version that incorporates these improvements.

 

R: These suggestions were incorporated throughout the manuscript in order to improve clarity and readability.

Reviewer 2 Report

Comments and Suggestions for Authors

General comment

The manuscript can benefit from English language editing

Abstract

The authors made the following statement:

‘ Bariatric surgery may be mandatory to improve nutritional status in obesity ‘

 

This statement seems conditional and may require further explanations. It seems odd to start with this statement in the abstract. Another statement indicating that there is a rise in obesity and the associated curative bariatric surgery might be more suitable to indicate the importance of the current investigation.

 

 

The authors made the following statement:

‘ Appropriate tests were employed (p<0.05).’

 

Please declare the name of these tests.

 

 

The results section of the abstract is not informative. Please add numbers depending on the applied tests to display the magnitude of change and levels of statistical significance.

 

 

Introduction

Is pre-obesity similar to overweight. please explain the difference and the indication of using both terminologies in the same section.

 

In line 47, the authors made the following statement:

 

‘The current Portuguese guidelines’

 

What are these guidelines? Please elaborate.

 

Sections of the introduction in lines 64 to 88 narrate the role of dietitians in their clinical practice. It is not clear how  this is relevant to the topic of the study. It does not provide clear notion pertaining to aim of the study. I would consider deletion of this section and provision of literature specifically associated with the  aim of the study which is declare as assessment of changes in anthropometric and body composition characteristics of patients undergoing metabolic and bariatric surgery.

 

Methods

 

Please declare the distribution of the data and its normality. This is important to justify why certain descriptive and inferential statistics are used.

                                                                                                                          

Results

Narration of the results is not organized. It starts with displaying findings via referring to the tables 1 , 2 , 3 and 4 and then returns back to discuss findings of table one. Please reorganize the results section.

 

Tables 1 - 4

Please explain the meaning of ‘Normoponderal’

 

Some cells include the value of 0. The table is confusing as it contains multiple empty cells, and some tests that were not possible to apply. Please consider revising the tables.  

 

Having multiple stratifications of the results is confusing. The current analysis can benefit from applying regression analysis to account for all factors in a single model instead of the repeated stratifications. 

 

 

Discussion

The discussion is lacking a conclusion section. What are the implications for clinical practice and future research?

 

 

Comments on the Quality of English Language

The manuscript can benefit from English language editing. 

Author Response

The authors acknowledge this important appreciation of the manuscript and express recognition for the useful comments and all the suggestions.

 

Reviewer 2

 

General comment

The manuscript can benefit from English language editing

 

R: The manuscript was revised in order to improve English language.

 

Abstract

The authors made the following statement:

‘ Bariatric surgery may be mandatory to improve nutritional status in obesity ‘

This statement seems conditional and may require further explanations. It seems odd to start with this statement in the abstract. Another statement indicating that there is a rise in obesity and the associated curative bariatric surgery might be more suitable to indicate the importance of the current investigation.

 

R: The abstract was changed accordingly:

“The rise in obesity and its associated health problems increases the need for therapeutic approaches such as bariatric surgery.”

 

The authors made the following statement:

‘ Appropriate tests were employed (p<0.05).’

 Please declare the name of these tests.

 

R: This information was added to abstract:

“Student's t-test and Mann-Whitney test were employed (p<0.05);”

 

The results section of the abstract is not informative. Please add numbers depending on the applied tests to display the magnitude of change and levels of statistical significance.

 

R: The numbers were added as indicated.

“Between pre-and post-surgical periods [63 (42) days], weight [mean: 103.0 (SD: 16.3) kg vs. 91.2 (14.2) kg, p<0.001], BMI [37.9 (4.2) kg/m2 vs. 33.6 (4.1) kg/m2, p<0.001], waist perimeter [116.2 (12.4) cm vs. 105.7 (12.3) cm, p<0.001], %fat mass [45.5 (6.0) vs. 41.0 (8.0), p<0.001], skeletal muscle mass [32.8 (7.4) kg vs. 30.3 (6.5) kg, p<0.001] and skeletal muscle mass index [12.0 (1.8) kg/m2 vs. 11.1 (1.7) kg/m2, p<0.001] decreased; %fat-free mass increased [54.7 (6.0) vs. 59.0 (8.0), p<0.001].”

 

Introduction

Is pre-obesity similar to overweight. please explain the difference and the indication of using both terminologies in the same section.

 

R: This was corrected in order to provide clarity.

 

In line 47, the authors made the following statement:

‘The current Portuguese guidelines’

What are these guidelines? Please elaborate.

 

R: These guidelines are from Portuguese General Directorate of Health. However are the same as other international guidelines. In order to provide clarity, this sentence was rewritten:

“The current Portuguese guidelines follow international standards and recommendations, and they state that the eligibility criteria for metabolic and bariatric surgery in adults are:”

 

Sections of the introduction in lines 64 to 88 narrate the role of dietitians in their clinical practice. It is not clear how this is relevant to the topic of the study. It does not provide clear notion pertaining to aim of the study. I would consider deletion of this section and provision of literature specifically associated with the  aim of the study which is declare as assessment of changes in anthropometric and body composition characteristics of patients undergoing metabolic and bariatric surgery.

 

R: This section was changed accordingly.

 

Methods

Please declare the distribution of the data and its normality. This is important to justify why certain descriptive and inferential statistics are used.

 

R: The normality of the variable’s distribution was tested using Kolmogorov-Smirnov test. This information was missing from methodology in the original manuscript and is now added:

“Data was tested for normal distribution using the Kolmogorov‑Smirnov test.”

                                                                                                                          

Results

Narration of the results is not organized. It starts with displaying findings via referring to the tables 1 , 2 , 3 and 4 and then returns back to discuss findings of table one. Please reorganize the results section.

 

R: Tables were changed in order to improve clarity and the narration of the results was rewritten accordingly.

 

Tables 1 - 4

Please explain the meaning of ‘Normoponderal’

 

R: “Normoponderal” means “Normal weight”. This was a mistake in the translation and it is now corrected throughout the manuscript text.

 

Some cells include the value of 0. The table is confusing as it contains multiple empty cells, and some tests that were not possible to apply. Please consider revising the tables.  

 

R: Tables were revised and changed in order to improve clarity.

 

Having multiple stratifications of the results is confusing. The current analysis can benefit from applying regression analysis to account for all factors in a single model instead of the repeated stratifications. 

 

R: Tables were revised and changed in order to improve clarity. Our low sample size does not allow us to conduct a regression analysis. This limitation was acknowledged and included in the discussion.

 

Discussion

The discussion is lacking a conclusion section. What are the implications for clinical practice and future research?

 

R: A conclusion section was included in the discussion. The implications for clinical practice and future research were also added in the Discussion.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Overall, the authors have addressed my concerns and suggestions in an adequate and effective manner. The manuscript has been extensively revised, resulting in a significant improvement in quality. The authors should be specifically commended for the more thorough and in-depth Discussion section. However, the extensive revisions have introduced some minor issues that should also be addressed prior to publication.

1) Please omit (or revise) the following sentence: "However, according to a randomized controlled trial, gastric bypass was superior to sleeve gastrectomy regarding weight loss and remission of diabetes at 3 years after surgery [9]." There is evidence suggesting quite the opposite - namely, that laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) are equivalent in terms of effectiveness at 5 years postoperatively (Peterli et al., 2018, DOIs: 10.1001/jama.2017.20897; Salminen et al., 2018, DOI: 10.1001/jama.2017.20313). Furthermore, patients undergoing LSG appear to have lower all-cause mortality compared to those undergoing RYGB (Holmberg et al., 2022, DOI: 10.2337/dc22-0485; Sakurai et al., 2024, DOI: 10.1016/j.soard.2024.11.016). It would be advisable to avoid delving into this debate, as it remains ongoing and the current evidence does not decisively favor one procedure over the other.

2) In Tables 1 and 2, please add a column next to each comparison indicating the respective p values. Overall, the tables are now more readable compared to the initial version of the manuscript.

Please address those issues and your manuscript will be ready for publication.

Author Response

The authors acknowledge the reviewers for this new appreciation of the manuscript and express recognition for the useful comments and all the suggestions.

 

Reviewer 1

 

Overall, the authors have addressed my concerns and suggestions in an adequate and effective manner. The manuscript has been extensively revised, resulting in a significant improvement in quality. The authors should be specifically commended for the more thorough and in-depth Discussion section. However, the extensive revisions have introduced some minor issues that should also be addressed prior to publication.

 

R: Thank you very much for your appreciation.

 

1) Please omit (or revise) the following sentence: "However, according to a randomized controlled trial, gastric bypass was superior to sleeve gastrectomy regarding weight loss and remission of diabetes at 3 years after surgery [9]." There is evidence suggesting quite the opposite - namely, that laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (RYGB) are equivalent in terms of effectiveness at 5 years postoperatively (Peterli et al., 2018, DOIs: 10.1001/jama.2017.20897; Salminen et al., 2018, DOI: 10.1001/jama.2017.20313). Furthermore, patients undergoing LSG appear to have lower all-cause mortality compared to those undergoing RYGB (Holmberg et al., 2022, DOI: 10.2337/dc22-0485; Sakurai et al., 2024, DOI: 10.1016/j.soard.2024.11.016). It would be advisable to avoid delving into this debate, as it remains ongoing and the current evidence does not decisively favor one procedure over the other.

 

R: Accordingly this sentence was removed from the manuscript.

 

2) In Tables 1 and 2, please add a column next to each comparison indicating the respective p values. Overall, the tables are now more readable compared to the initial version of the manuscript.

 

R: p values were added to both Tables 1 and 2.

 

Please address those issues and your manuscript will be ready for publication.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors made a good effort in addressing all comments except for the following comment: 

 

Sections of the introduction in lines 64 to 88 narrate the role of dietitians in their clinical practice. It is not clear how this is relevant to the topic of the study. It does not provide clear notion pertaining to aim of the study. I would consider deletion of this section and provision of literature specifically associated with the  aim of the study which is declare as assessment of changes in anthropometric and body composition characteristics of patients undergoing metabolic and bariatric surgery.

Their response was: 

R: This section was changed accordingly.

The change is not clear for this reviewer. Additionally, It is still not clear why this section is important for the current manuscript.

 

Otherwise, all other concerns were addressed 

Author Response

The authors acknowledge the reviewers for this new appreciation of the manuscript and express recognition for the useful comments and all the suggestions.

 

Reviewer 2

 

The authors made a good effort in addressing all comments except for the following comment:

 

Sections of the introduction in lines 64 to 88 narrate the role of dietitians in their clinical practice. It is not clear how this is relevant to the topic of the study. It does not provide clear notion pertaining to aim of the study. I would consider deletion of this section and provision of literature specifically associated with the  aim of the study which is declare as assessment of changes in anthropometric and body composition characteristics of patients undergoing metabolic and bariatric surgery.

Their response was:

R: This section was changed accordingly.

The change is not clear for this reviewer. Additionally, It is still not clear why this section is important for the current manuscript.

 

R: Firstly, we apologize for the misinterpretation of your previous comment on this issue. We removed from the manuscript the sentences related to the role of the dieticians and we added references related to the aim of our study, namely references 6 and 9.

 

Otherwise, all other concerns were addressed

 

R: Thank you.

Author Response File: Author Response.pdf