Associations Between Binge-Eating Symptoms and Chronotype Among Bariatric Surgery Candidates: Clinical Implications for Preoperative Assessment—A Cross-Sectional Study

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors, your manuscript presented to this journal is interesting; however, there are some comments to improve your work. In the next lines, you can find my recommendations. 

1. Please indicate in the title the study design followed to do this work, this to alliang us in the political recommendation to better indexation. 
2. In the introduction section, you should incorporate some information about the relevance of doing this research in the bariatric population 
3. In the methods section, please clarify if all the instruments/tools used in this research are routinely applied to all the bariatric candidates in this clinic to do an adequate prospective analysis. 
4. It is unclear whether all participants in this research completed all the requirements to be considered as bariatric candidates. This is due to the increasing number of people seeking bariatric surgery to control obesity and other metabolic diseases, but without trying other therapies that should be applied before surgery (10.1016/j.cireng.2019.05.016, 10.1016/j.jpeds.2025.114564). 
5. In the procedures section, the authors have informed that: "All questionnaires used were applied remotely, while the remaining data was collected during the appointments with the multidisciplinary team, as further specified below." So is this the regular procedure at the clinic? This could look like the research was done prospectively, not a retrospective one. 
6. The statistical analysis presented in this research could be improved with an analysis of regression models to try to elucidate other confounding factors that could impact your results, prior to doing the moderation analysis. 
7. In all the tables, the results try to present the % of n for a better analysis. 
8. The table that supports the moderation analysis is not found in the manuscript. 
9. Your results, even when they were not statistically significant, are important to improve the reproducibility of science. So, in the discussion section, please give more information about the differences in the prevalence of BED due to the diagnostic criteria. On the other hand, please discuss the possible role of the previous attempts to lose weight in the bariatric candidates that could impact the eating behaviour analysed in this research. 
10. To confirm some of your results, it would be more adequate to include data from a control group, for example, people without obesity.

Author Response

We thank the reviewers for the careful reading and constructive suggestions. Below we respond to each major and minor point and describe the specific revisions made in the manuscript. All changes are highlighted in the revised manuscript.

Dear authors, your manuscript presented to this journal is interesting; however, there are some comments to improve your work. In the next lines, you can find my recommendations. 

• Comment 1: Please indicate in the title the study design followed to do this work, this to align us in the political recommendation to better indexation. 
  • Answer: As requested, the study design was indicated in the title, as “a cross-sectional study”.

 

• Comment 2: In the introduction section, you should incorporate some information about the relevance of doing this research in the bariatric population 
  • Answer: We agree that this is an important addition. We expanded the Introduction to include a paragraph describing it in further detail. The following sentences have been added to the manuscript.
  • Introduction (lines 55-66): “Patients who are candidates for bariatric surgery represent a subgroup of individuals with severe obesity who frequently present with disordered eating patterns, sleep disorders, and psychiatric comorbidities that may influence postoperative prognosis. A more refined assessment of behavioral and chronobiological factors (e.g., chronotype) in this population is relevant because it may assist in postoperative planning and in developing sleep-related recommendations tailored to each patient's characteristics (19)”

 

• In the methods section, please clarify if all the instruments/tools used in this research are routinely applied to all the bariatric candidates in this clinic to do an adequate prospective analysis. 
  • Answer: All questionnaires used in this study are part of the standard preoperative evaluation routinely conducted at the clinic. The following sentence was added to the methods section to make it clearer.
  • Materials and Methods – Procedures (lines 118-122): “All data collection tools and procedures are part of the clinic’s preoperative standard care routine, which were not modified for the interests of this study. This includes all questionnaires, which were collected remotely through online forms, and all clinical data, which are collected in appointments with the multiprofessional team.”

 

 

• It is unclear whether all participants in this research completed all the requirements to be considered as bariatric candidates. This is due to the increasing number of people seeking bariatric surgery to control obesity and other metabolic diseases, but without trying other therapies that should be applied before surgery (10.1016/j.cireng.2019.05.016, 10.1016/j.jpeds.2025.114564). 

 

• Answer: We have clarified that all participants had completed the full multidisciplinary preoperative evaluation required by the clinic and met eligibility criteria for bariatric surgery according to current national and institutional guidelines. A description of these requirements has been added to the Methods section.
• Materials and Methods – Participants and study design (lines 86-95): “All patients fulfilled the required criteria for undergoing bariatric surgery according to Brazil’s National Supplementary Health Agency, which requires candidates to meet one of the following criteria: (i) a Body Mass Index (BMI) ≥ 40 kg/m², even in the absence of comorbidities; or (ii) a BMI between 35 and 39.9 kg/m² accompanied by at least one obesity-related comorbidity (e.g., type 2 diabetes, hypertension, sleep apnea, dyslipidemia, disabling joint diseases, cardiovascular disease, polycystic ovary syndrome, non-alcoholic fatty liver disease, endometriosis, rheumatic diseases, or difficult-to-control asthma). In addition, the agency requires candidates to undergo evaluation by at least four specialists: an endocrinologist, a psychologist, a nutritionist, and a cardiologist.”

 

 

• In the procedures section, the authors have informed that: "All questionnaires used were applied remotely, while the remaining data was collected during the appointments with the multidisciplinary team, as further specified below." So is this the regular procedure at the clinic? This could look like the research was done prospectively, not a retrospective one. 

 

• Answer: All questionnaires were applied remotely through online forms as part of the standard preoperative procedures in this clinic. The research team had no participation in collecting this data, which was delivered for research purposes as a database. The following sentence was added to the methods section.
• Materials and Methods – Procedures (lines 118-122): “All data collection tools and procedures are part of the clinic’s preoperative standard care routine, which were not modified for the interests of this study. This includes all questionnaires, which were collected remotely through online forms, and all clinical data, which are collected in appointments with the multiprofessional team.”

 

• The statistical analysis presented in this research could be improved with an analysis of regression models to try to elucidate other confounding factors that could impact your results, prior to doing the moderation analysis. 

 

• Answer: We conducted multivariate regression analyses including the covariates recommended by Reviewer 2 (age, sex, BMI, sleep quality, and insomnia severity). These variables were incorporated into the moderation analysis to control for potential confounding factors. The adjusted results indicated that the main findings were preserved, reinforcing the robustness of the observed effects. The following sentences were added to the manuscript.
• Methods – Statistical analysis (lines 174-178): “Finally, a multivariate linear regression was conducted controlling for age, sex, BMI, insomnia severity, and sleep quality. Subsequently, a moderation analysis was performed to evaluate the moderating effect of chronotype on the relationship between depression, anxiety, and stress (predictor variables) and binge eating scores (dependent variable).”

 

• In all the tables, the results try to present the % of n for a better analysis. 

 

• Percentages were added to the tables, as requested.

 

• The table that supports the moderation analysis is not found in the manuscript. 

 

• Thank you for noticing this omission. We have now included the full table with an analysis of regression models.

 

• Your results, even when they were not statistically significant, are important to improve the reproducibility of science. So, in the discussion section, please give more information about the differences in the prevalence of BED due to the diagnostic criteria. On the other hand, please discuss the possible role of the previous attempts to lose weight in the bariatric candidates that could impact the eating behaviour analysed in this research. 
  • Thank you for these suggestions. We have added the following paragraphs to the discussion section to encompass these topics.
  • Discussion (lines 296-304): “Bariatric surgery candidates typically report long trajectories of repeated dieting and weight regain; patterns consistently linked to increased risk of binge-eating behaviors (36, 37). Recurrent dieting can influence appetite regulation, cognitive restraint, and loss-of-control eating, which may exert a strong effect on binge-eating severity. Because these dieting histories tend to be highly prevalent and influential among individuals seeking bariatric surgery, they may have contributed to homogenizing binge-eating patterns across chronotypes. Since dieting history was not collected, future studies should evaluate this factor as a potential determinant of binge eating in this population.”
  • Discussion (lines 322-332): “It is also important to acknowledge that the use of the Binge Eating Scale (BES) represents a methodological limitation when interpreting the prevalence of binge-eating symptoms in our sample. The BES is a screening instrument that quantifies the severity of binge-eating symptoms, but it does not provide a formal diagnosis of Binge Eating Disorder (BED) according to DSM-5 criteria, which require the presence of objective binge episodes, loss of control, marked distress, and a minimum frequency and duration. Consequently, the prevalence observed in our study reflects symptom severity rather than diagnostic-level BED, which may partially explain discrepancies with studies reporting BED prevalence using structured clinical interviews. This distinction is relevant for interpreting our null findings, as symptom-based scales may capture a broader and more heterogeneous phenotype, possibly diluting the associations between chronotype and clinically defined BED.”

 

• To confirm some of your results, it would be more adequate to include data from a control group, for example, people without obesity.

 

• Answer: We acknowledge this valuable suggestion. Unfortunately, the inclusion of a control group composed of individuals with no obesity was beyond the scope of the current study and not feasible due to the site and conditions from which the sample was collected. In any case, we have added this point to the Limitations section and discussed it as an important direction for future research.
• Discussion (lines 337-339): “Finally, another important limitation of this study is the inability to compare data on binge eating and chronotype with a population without obesity, since the impulsive component may be related to chronotype rather than to obesity itself.”

Reviewer 2 Report

Comments and Suggestions for Authors

Dear Authors,

The study investigate whether chronotype is associated with binge eating in a sample of 100 bariatric surgery candidates. Chronotype was measured and additional sleep and psychological variables were assessed through validated self-report instruments. The authors report a high prevalence of binge eating but no significant association with chronotype.

This topic is clinically relevant and understudied in bariatric populations. The data are potentially valuable; however, substantial methodological, analytical, and conceptual revisions are required before the manuscript is suitable for publication.

Major strengths are: Relevant research question; Clinically meaningful sample; Use of validated instruments; Clear reporting of procedures and Negative findings contribute to literature (given inconsistent evidence in the field, reporting null associations has value).

 

Require Substantial Revision

Insufficient statistical modelling: The analyses rely exclusively on ANOVA, chi-square tests, and simple moderation. This is inadequate for a research question involving multiple interacting behavioral, psychological, and sleep variables. Authors can: Implement multivariate regression models (linear for BES, logistic for binge-eating categories); Adjust for key covariates: age, sex, BMI, depression, anxiety, sleep quality, insomnia severity. Report effect sizes and confidence intervals, not only p-values.

Without these adjustments, conclusions regarding the absence of association between chronotype and binge eating lack robustness.

Conceptual inaccuracies: Clarify distinctions among chronotype, circadian alignment, and sleep health.

Use of BES as the sole measure of binge eating: The Binge Eating Scale is a screening instrument; it does not diagnose binge-eating episodes nor binge-eating disorder (BED). Please, clearly state that the study measures binge-eating severity symptoms, not diagnostic binge eating and adjust language throughout to avoid over-interpretation.

Excessive speculation in the Discussion: Explanations for null findings (e.g., “obesity overshadowing chronotype effects”) are speculative without empirical support. It´s better reduce speculation; focus on data-driven interpretations and clearly differentiate between hypotheses and evidence.

Missing data in table 3: Table 3. ISI - Insomnia symptoms - Severe (n=4; 0,00%)????

 

Require Minor Revision - These issues are not severe but should be clarified.

1) English phrasing issues: Several grammatical errors, awkward constructions, and non-standard terms (“food compulsion”) require correction. 2) Long sentences: Several paragraphs (especially in Discussion) need restructuring for clarity. 3) Terminology inconsistencies: Maintain uniform terminology across sections (e.g., binge eating vs. binge-eating behavior). 4) Figures need clearer legends: Some figure panels require more descriptive captions for readers unfamiliar with the measures.

 

Decision: Major Revision: The manuscript has scientific merit and the dataset is clinically valuable. However, substantial revisions are required, particularly concerning statistical modeling, conceptual clarity, discussion structure, and language quality. If you address the major concerns—particularly by implementing appropriate multivariate analyses and revising the discussion.

 

Comments on the Quality of English Language

English should be improved.

 

Author Response

We thank the reviewers for the careful reading and constructive suggestions. Below we respond to each major and minor point and describe the specific revisions made in the manuscript. All changes are highlighted in the revised manuscript.

 

Dear Authors,

The study investigate whether chronotype is associated with binge eating in a sample of 100 bariatric surgery candidates. Chronotype was measured and additional sleep and psychological variables were assessed through validated self-report instruments. The authors report a high prevalence of binge eating but no significant association with chronotype. This topic is clinically relevant and understudied in bariatric populations. The data are potentially valuable; however, substantial methodological, analytical, and conceptual revisions are required before the manuscript is suitable for publication. Major strengths are: Relevant research question; Clinically meaningful sample; Use of validated instruments; Clear reporting of procedures and Negative findings contribute to literature (given inconsistent evidence in the field, reporting null associations has value).

• Insufficient statistical modelling: The analyses rely exclusively on ANOVA, chi-square tests, and simple moderation. This is inadequate for a research question involving multiple interacting behavioral, psychological, and sleep variables. Authors can:Implement multivariate regression models (linear for BES, logistic for binge-eating categories); Adjust for key covariates: age, sex, BMI, depression, anxiety, sleep quality, insomnia severity. Report effect sizes and confidence intervals, not only p-values. Without these adjustments, conclusions regarding the absence of association between chronotype and binge eating lack robustness.
  • Answer: We conducted multivariate regression analyses including the covariates recommended (age, sex, BMI, sleep quality, and insomnia severity). We chose to conduct only linear regression analyses, as the small sample size restricts the inclusion of multiple associations in more complex models. These variables were incorporated into the moderation analysis to control potential confounding factors. The adjusted results indicated that the main findings were preserved, reinforcing the robustness of the observed effects. All these results are now described in Table 5. The following modifications addressing the new analyses were added to the manuscript.
  • Methods – Statistical analysis (lines 174-178): “Finally, a multivariate linear regression was conducted controlling for age, sex, BMI, insomnia severity, and sleep quality. Subsequently, a moderation analysis was performed to evaluate the moderating effect of chronotype on the relationship between depression, anxiety, and stress (predictor variables) and binge eating symptoms scores (dependent variable).”
  • Results – Chronotype and binge eating symptoms (lines 228-237): “Across all models, neither stress, anxiety, nor depression significantly predicted binge eating scores after adjusting for covariates (sex, age, BMI, insomnia symptoms, and sleep quality) (Table 5). Similarly, chronotype did not show significant main effects on binge eating in any comparison (morning–evening, morning–intermediate, or intermediate–evening types). Interaction terms between chronotype and each psychological factor (stress, anxiety, and depression) were also non-significant, indicating no evidence of moderation. Overall, the confidence intervals for all predictors and interactions included zero, and p-values remained well above the conventional significance threshold, suggesting that none of the psychological variables nor chronotype—alone or in combination—were associated with binge-eating severity in this sample.”

 

• Conceptual inaccuracies: Clarify distinctions among chronotype, circadian alignment, and sleep health.
  • Answer: We agree on the need to be scientifically precise on the use of these terms, specifically considering that the journal’s readership may not be primarily keen to sleep medicine jargon. That said, a few clarifications shall be made on the usage of these three terms and how we implemented them into the manuscript.
    • Chronotype: Among the three terms mentioned by the Reviewer, this is the only that was consistently used in our manuscript, as it corresponds to a main feature of our hypothesis and our outcomes.
    • Circadian alignment: This is a rather uncommon term, not used in our manuscript and even scarcely used in the literature in general (only 20 records in PubMed). Another possible term would be “circadian misalignment”, which although more frequently used in the literature (158 records in PubMed), has a dubious meaning, being at some points used to refer to conditions in which the circadian rhythm is out of phase with the natural light-dark cycle (ex.: non-24h sleep disorder, or delayed sleep-wake rhythm disorder) or due to social conditions that prevents a natural sleep-wake cycle to be performed (ex.: social jetlag and shift work). In any case, none of these terms were used in our manuscript. Therefore, rather than distinguishing chronotype from other imprecise terms, we stick to our previous approach and prefer not to use terms that we consider as non-standard. To avoid confusions, the only two mentioned to the word “alignment” in the original manuscript were replaced by other terms, specifically when referring to social jetlag.
    • Sleep health: This is an important term that has been increasingly used in literature. However, it has not been even used in the previous manuscript, how we are not sure about how or why a distinction between it and chronotype would be needed. Of note, this is a rather subjective term, which although well-understood in its own, is not primarily related to the goals of this manuscript. Therefore, rather than diving into technical discussion about “sleep health”, we stick to our first approach, focusing more on chronotype as our mains focus.

Considering the above, the sentences below have been added to the manuscript, to further detail chronotype and its relationship with related concepts.

• Introduction (lines 55-66): “Chronotypes are phenotypes related to the temporal organization of someone’s activities, including the preferred waking and sleeping times (11). Chronotypes are usually regarded as a psychological trait, as a personal circadian preference for sleep, and the performance of daytime activities, although recent evidence suggests that a significant part of it is bio-logically determined (11, 12). In humans, there are three well-defined chronotypes – morning-types, intermediate types and evening-types. Discrepancies between an individual’s chronotype (the behavioral expression of their biological clock) and the geophysical cycle has been associated with poorer cognitive and behavioral outcomes, and even to worsen or trigger mental health conditions (13). In most cases, poorer cognitive and behavioral profiles have been linked to the evening chronotype, largely due to chronic mismatch between the internal biological clock and social obligations – commonly referred to as social jetlag (11)”.

 

 

• Use of BES as the sole measure of binge eating: The Binge Eating Scale is a screening instrument; it does not diagnose binge-eating episodes nor binge-eating disorder (BED). Please, clearly state that the study measures binge-eating severity symptoms, not diagnostic binge eating and adjust language throughout to avoid over-interpretation.
  • Answer: We agree BES cannot provide a clinically reliable diagnosis of binge eating. Therefore, we have revised the whole manuscript to assure we refer specifically to binge eating symptoms. Also, we have added the following sentences to the Limitations section
  • Discussion (lines 322-332): “It is also important to acknowledge that the use of the Binge Eating Scale (BES) represents a methodological limitation when interpreting the prevalence of binge-eating symptoms in our sample. The BES is a screening instrument that quantifies the severity of binge-eating symptoms, but it does not provide a formal diagnosis of Binge Eating Disorder (BED) according to DSM-5 criteria, which require the presence of objective binge episodes, loss of control, marked distress, and a minimum frequency and duration. Consequently, the prevalence observed in our study reflects symptom severity rather than diagnostic-level BED, which may partially explain discrepancies with studies reporting BED prevalence using structured clinical interviews. This distinction is relevant for interpreting our null findings, as symptom-based scales may capture a broader and more heterogeneous phenotype, possibly diluting the associations between chronotype and clinically defined BED.”

 

• Excessive speculation in the Discussion: Explanations for null findings (e.g., “obesity overshadowing chronotype effects”) are speculative without empirical support. It´s better reduce speculation; focus on data-driven interpretations and clearly differentiate between hypotheses and evidence.
  • We edited the Discussion to reduce speculative language. Hypotheses about mechanisms (e.g., hormonal changes, impulsivity) are now presented as tentative and clearly labeled as hypotheses rather than conclusions. We also shortened speculative paragraphs and increased emphasis on data-driven explanations and limitations. Specific sentences were reworded to avoid strong causal claims.

 

• Missing data in table 3: Table 3. ISI - Insomnia symptoms - Severe (n=4; 0,00%)????
  • Answer: All tables were carefully revised corrections have been implemented as requested, to solve typos and other errors.

 

• Require Minor Revision -These issues are not severe but should be clarified. English phrasing issues: Several grammatical errors, awkward constructions, and non-standard terms (“food compulsion”) require correction. 2) Long sentences: Several paragraphs (especially in Discussion) need restructuring for clarity. 3) Terminology inconsistencies: Maintain uniform terminology across sections (e.g., binge eating vs. binge-eating behavior). 4) Figures need clearer legends: Some figure panels require more descriptive captions for readers unfamiliar with the measures.
  • Answer: We conducted a comprehensive language edit across the manuscript to correct grammar, improve reading flow, and standardize terminology, as requested. Sentences that were excessively long were split; ambiguous terms (e.g., “food compulsion”) were replaced with standard terminology. Figure legends for Figures 1 and 2 were rewritten to be more informative and self-contained. Example: Figure 1 legend now specifies MEQ categories and the reason for regrouping into three categories. Figure 2 legend clarifies that BES categories correspond to symptom severity and provides definitions.

 

 

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear authors, thanks for the new version of your manuscript. In this version, you have improved the work. 

Reviewer 2 Report

Comments and Suggestions for Authors

Nothing to add. Corrections have been made to the reviewer's comments.