Eating Disorders and Behaviors / Obesity and Health Practices · Journal article

Mental health in individuals who have undergone metabolic bariatric surgery: a cross-sectional study using mediation analysis

Scientific Reports · August 17, 2026

Promising Why this matters to you Expert discussion

Encouraging direction, but not yet definitive.

AI Summary

This cross-sectional study of 238 post-bariatric surgery adults used mediation analysis to identify emotion regulation difficulties and body image concerns as pathways linking obesity to depression, anxiety, and stress symptoms. Depression and stress were higher in those with longer time since surgery, suggesting mental health deterioration despite initial treatment benefits; however, the observational design precludes causal inference and clinical outcomes are not measured.

What was studied

Cross-sectional study with mediation analysis. Adults with history of metabolic bariatric surgery; 238 individuals assessed with DASS-21, DERS-SF, and BIS.. Intervention: History of metabolic bariatric surgery. n = 238.

Key findings

Higher DASS-Depression scores (β = 2.09, p = 0.03) in individuals with longer time since MBS compared to recent surgery Higher DASS-Stress scores (β = 2.49, p = 0.01) with longer post-surgical interval DERS-SF Strategies mediated obesity-depression association (Boot β = 0.81; 95% CI [0.21, 1.93]; p = 0.005)

Safety

Safety was not reported in the material analysed. Check the source before drawing any conclusion about harm.

Who this may help

Clinicians should recognize that depression, anxiety, and stress symptoms may emerge or worsen years after bariatric surgery, particularly in patients with persistent obesity, emotion regulation difficulties, or body image concerns. This suggests the need for structured mental health monitoring and targeted psychological intervention post-surgery, but the observational design does not establish causation and requires validation in prospective studies.

Plain-language summary

Cross-sectional study with clear mediation findings in a defined post-surgical population; sound statistical approach but observational design and lack of clinical outcome validation limit strength.

Study design

As stated by the source record.

MethodsA sample of 238 adults with history of MBS completed the DASS-21, DERS-SF, and BIS scales. Regression and mediation models (bootstrap method) were employed to investigate associations between obesity, emotion regulation difficulties, body image, and mental health outcomes (depression, anxiety, stress). The analysis examined both direct effects of time since surgery and indirect effects through emotion regulation and body investment pathways.

DesignCross-sectional study with mediation analysis

PopulationAdults with history of metabolic bariatric surgery; 238 individuals assessed with DASS-21, DERS-SF, and BIS.

Sample size238

InterventionHistory of metabolic bariatric surgery

Reported figures

Quoted from the source exactly as published.

Sample size238

DASS-Depression in longer post-MBS interval (regression coefficient)β = 2.09

DASS-Depression p-value (time since MBS)p = 0.03

DASS-Stress in longer post-MBS interval (regression coefficient)β = 2.49

DASS-Stress p-value (time since MBS)p = 0.01

DERS-SF Strategies mediation of obesity-depression (bootstrap coefficient)Boot β = 0.81

DERS-SF Strategies 95% CI[0.21, 1.93]

DERS-SF Strategies p-valuep = 0.005

Clinical bottom line

Caveats

Cross-sectional design cannot establish temporal sequence or causality; mediation analysis is exploratory pending prospective confirmation
Mental health assessed by self-report symptom scales (DASS-21) only; no clinical diagnosis, psychiatric evaluation, or medication status reported
No comparison group (e.g., non-surgical obese controls, early post-operative cohort); time since surgery analysed as continuous variable without detail on distribution or cutoffs
Demographic characteristics, bariatric surgery types, weight loss outcomes, and potential confounders (e.g., comorbidities, medications) not described

Evidence assessment

Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.

Study design

moderate

Cross-sectional design; no randomization or comparison group; mediation analysis appropriate for hypothesis generation.

Directness

moderate

Self-reported symptom scales (DASS-21) used; clinical diagnoses not reported; surrogate endpoints.

Consistency

limited

Single study; no comparator data provided; mediation pathways identified but not previously validated in this population.

Risk of bias

limited

Cross-sectional; selection and recall bias possible; no blinding; no discussion of confounding or missing data.

Sample adequacy

moderate

n=238 adequate for mediation; post-hoc power not reported; generalizability to broader MBS population unclear.

Source abstract

This study investigated factors associated with mental health outcomes in individuals who have undergone Metabolic Bariatric Surgery (MBS). A sample of 238 adults with history of MBS was assessed with the 21-item Depression and Anxiety Stress Scale (DASS-21), Difficulties in Emotion Regulation Scale (DERS-SF), and the 24-item Body Investment Scale (BIS). Regression and mediation models were employed to investigate factors associated with mental health outcomes. Higher levels of DASS-Depression (β = 2.09, p = 0.03), and DASS-Stress scores (β = 2.49, p = 0.01) were found in individual who have undergone MBS longer ago, in comparison with individuals who underwent MBS more recently. DERS-SF emotion regulation dimensions Strategies (Boot β = 0.81; 95%CI: [0.21, 1.93]; p = 0.005), and BIS dimension Body-Image (Boot β = 1.10; 95%CI: [0.48, 2.03]; p < 0.001), were found to significantly mediate the association between obesity and DASS-21 Depression. BIS-Body image also mediated the association between obesity and DASS-21 Anxiety (Boot β = 0.67; 95%CI: [0.14, 1.38]; p = 0.009) and DASS-21 Stress (Boot β = 1.97; 95%CI: [0.57, 3.86]; p < 0.002). Mental health problems might be present in individuals who have undergone MBS long time ago, despite potential treatment benefits, with presence of obesity and specific emotion regulation and body-investment difficulties being associated with greater depression, anxiety and stress symptomatology.

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Eating Disorders and BehaviorsHugo SenraObesity and Health PracticesJoana HenriquesVera AfreixoHuman Unterrainer