Background Laparoscopic sleeve gastrectomy (LSG) is a restrictive bariatric surgery procedure and currently the second most performed technique worldwide. Follow-up data on depression, stress and eating behaviour are scarce. The aim of this longitudinal study was to investigate the medium-term effects of LSG on mental health and eating behaviour and their influence on weight loss by using a comprehensive interview-based assessment. Methods Seventy-five individuals, who had undergone LSG at a university hospital, were included in the study. Symptoms of disordered eating were assessed using a structured clinical interview (eating disorder examination) and the Three-Factor Eating Questionnaire with depressive symptoms and stress assessed via the Patient Health Questionnaire. Results Mean interval from LSG to follow-up (FU) examination was 48+/-13.3 months. The total body weight loss was 24.2 +/-12.0 %. Depressive symptom scores improved from pre-operative to FU (9 [IQR 5-14] vs. 6 [IQR 2-10], p = 0.002) as did stress scores (8.7 +/- 4.6 vs. 6.3 +/- 4.7, p=0.001). At FU, 11 % of patients reported loss-of-control eating and 39 % grazing, paralleled by increased body mass index, stress and depressive symptoms. Prior to LSG, nine patients fulfilled the diagnostic criteria of binge eating disorder but only one at FU. Conclusions Post-surgical mental health appears to be highly relevant in terms of weight loss maintenance. It is likely that the surgical outcome could be positively influenced if patients at risk of developing mental health issues or eating disorders were identified and monitored in order to offer targeted interventions.