Individuals who undergo bariatric surgery expect weight loss results. However, the surgical procedure can have varying effects on the psychological health of patients, too. Research shows both adults and adolescents may experience improvements in quality of life and depression, while other studies find an increased rate of depression and other unfavorable mental health outcomes following bariatric surgery.
The Long-Term Adverse Effects of Bariatric Surgery on Mental Health
Not all patients achieve favorable postoperative mental health outcomes. Research from a systematic review and meta-analysis reported that symptoms of depression remained elevated after bariatric surgery relative to the general population.2
For example, adolescents aged 13 to 18 years who underwent bariatric surgery had a reduced body mass index (BMI) from baseline to 1 and 2 years (median, 45.6 vs 30.9 vs 30.1 kg/m2; both P <.001), respectively. While this weight loss was accompanied by improvements in depression (both P <.001), anxiety (both P <.001), obesity-related problems (both P <.001), self-concept (both P <.001), self-esteem (both P <.001), pleasantness (both P ≤.015), overall mood (both P ≤.025), calmness (both P ≤.027), and disruptive behavior (both P ≤.048), compared with age-matched norms, adolescents who underwent bariatric surgery had worse mood. Furthermore, nearly a fifth (19%) met the clinical definition of depression at 2 years.4
In addition to evidence of worse health-related quality of life (HRQOL) after bariatric surgery relative to the general population, some evidence indicates that improvements to HRQOL after bariatric surgery may diminish with time.1,5
Research from a systematic review and meta-analysis reported that symptoms of depression remained elevated after bariatric surgery relative to the general population.
For example, for youth aged 14 to 16 years who had a BMI of at least 40 kg/m2 or at least 35 kg/m2 with obesity-related comorbidities, bariatric surgery combined with a multidisciplinary lifestyle intervention (MLI) resulted in a 5.29-kg/m2 greater reduction at 12 months and a 3.43-kg/m2 greater reduction at 24 months relative to MLI alone. Bariatric surgery was also associated with improved HRQOL scores at 12 months (treatment effect, 11.95; P =.009), driven by emotional component scores (treatment effect, 9.54; P =.05). At 24 months, however, youth who received bariatric surgery plus MLI did not have better HRQOL than those who received MLI alone (P =.11).1
Similarly, among adults aged mean 43.7 years, the proportion of individuals meeting the clinical criteria for depression was significantly reduced from 45% before bariatric surgery to 12% at 6 months (P <.001). However, the proportion of those meeting the criteria for depression continued to increase with time, from 13% at 12 months to 18% at 24 months, in which the rate of clinically significant depression was significantly higher at 24 months relative to 6 months after bariatric surgery (P =.02).5
One study identified that adults with worse psychological functioning after bariatric surgery desired to lose at least 40% of their body weight (b range, -6.0 to -4.5; both P £.004) and were unemployed before their surgery (b, -6.6; P <.001).
Of note, among the adults with postbariatric surgery depression at 24 months, depression was associated with eating disorder psychopathology (b, 0.472; P <.001), physical health (b, 0.410; P <.001), and mental health (b, 0.771; P <.001) but was not related with the amount of weight lost (b, 0.107; P =.186).5
When Bariatric Surgery Improves Mental Health
Research also shows favorable mental health outcomes following bariatric surgery.
In a systematic review and meta-analysis, bariatric surgery was associated with reduced symptoms of depression at 0 to 4 months (g, -0.59; I2, 80.55%; P =0.00), 5 to 12 months (g, -0.91; I2, 94.51%; P =0.00), and longer than 12 months (g, -0.68; I2, 83.55%; P =0.00).2
Recent evidence presented at the American Society for Metabolic and Bariatric Surgery (ASMBS) Annual Scientific Meeting in 2025 underscored this trend. The research described that adults who underwent bariatric surgery were less likely to have cognitive deficits (HR, 0.36; 95% CI, 0.23-0.58), anxiety disorders (HR, 0.60; 95% CI, 0.55-0.66), and substance use disorders (HR, 0.61; 95% CI, 0.54-0.74) at 5 years than propensity score-matched adults who used glucagon-like peptide-1 receptor agonists (GLP-1RAs).3
However, the positive effects of bariatric surgery on HRQOL and mental health outcomes may not be directly related with its weight loss effects.5,7
The Cognitive Effects of Bariatric Surgery
One study that enrolled adults undergoing bariatric surgery used a battery of questionnaires at baseline and 21 to 80 months to assess the relationship between weight loss and mental health outcomes. The authors reported no significant correlation between changes in depression scores and percent of excess body weight lost (P <.79). Instead, they found that negative body image mediated the relationship between depression and weight loss (P <.05). In the subgroup analysis, this trend was found to be driven by the subset of individuals who had poor body image at baseline, which improved with bariatric surgery-associated weight loss. Together, these data suggest that weight loss with bariatric surgery triggers complex behavioral and cognitive changes.7
These multifaceted mental health changes may be related with structural connectivity alterations in the brain after bariatric surgery. For instance, one study identified an increase in connectivity between the habenula and hypothalamus that correlated with reduced depression scores after bariatric surgery (r, -0.53; P =.012).8
Need for Presurgical Mental Health Screening
Given this body of evidence, the ASMBS recommends careful patient selection for bariatric surgery by conducting a presurgical psychosocial evaluation. The ASMBS emphasizes that mental health providers who have expertise in bariatric surgery are an important component to a multidisciplinary care team and can help determine which patients will be able to cope with the changes to their body image and lifestyle after surgery.10 The primary objective of a presurgical mental health evaluation is to identify risk for adverse postoperative outcomes such that patients can be referred to behavioral health resources in a timely manner.11