<b><i>Introduction:</i></b> The association between obesity and depression has been repeatedly established. However, little is known about the impact that the diagnosis of depression before bariatric surgery (DDBS) may have on weight loss. <b><i>Objective:</i></b> To evaluate the impact of DDBS on weight outcomes. <b><i>Methods:</i></b> Retrospective study of patients submitted to BS. Patients with no weight, no current medication data, or those submitted to revision surgery were excluded. Patients were considered to have DDBS based on taking antidepressants prior to BS or if there was a medical history of past or current depression. Patients with and without a depression history were compared using independent t test. A multivariate logistic regression model was created to evaluate predictors of weight variation (variables included: age, sex, and type of surgery). <b><i>Results:</i></b> A total of 616 patients did not have a history of depression and 230 had DDBS. There was a statistically significant difference in the BMI variation between groups. On average, individuals with DDBS lost 1.4 kg/m² less than those without DDBS. In the multivariate analysis, the group with DDBS, compared with the group without DDBS, presented on average less –0.9 kg/m² (95% CI –1.7 to –0.2, <i>p</i> = 0.018) BMI variation. <b><i>Conclusion:</i></b> DDBS is a predictor of lower weight loss after the surgical procedure. Even after adjusting for confounding variables such as age, sex, and BS type, this effect remains.