Introduction The prevalence and clinical significance of weight regain after bariatric surgery remains largely unclear due to the lack of a standardized definition of significant weight regain. The development of a clinically relevant definition of weight regain requires a better understanding of its clinical significance. Objectives To assess rates of weight regain 5 years after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG), applying six definitions and investigating their association with clinical outcomes. Methods Patients were followed up until 5 years after surgery and weight regain was calculated. Regression techniques were used to assess the association of weight regain with health-related quality of life (HRQoL) and the presence of comorbidities. Results A total of 868 patients participated in the study, with a mean age of 46.6 (± 10.4) years, of which 79% were female. The average preoperative BMI was 44.8 (± 5.9) kg/m 2 and the total maximum weight loss was 32% (± 8%). Eighty-seven percent experienced any regain. Significant weight regain rates ranged from 16 to 37% depending on the definition. Three weight regain definitions were associated with deterioration in physical HRQoL (p < 0.05), while associations between definitions of weight regain and the presence of comorbidities 5 years after surgery were not significant. Conclusion These results indicate that identifying one single categorical definition of clinically significant weight regain is difficult. Additional research into the clinical significance of weight regain is needed to inform the development of a standardized definition that includes all dimensions of surgery success: weight, HRQoL, and comorbidity remission. Keywords Weight regain. Health-related quality of life. Roux-en-Y gastric bypass. Sleeve gastrectomy. Long-term follow-up * Vera Voorwinde

Background Insufficient weight loss and weight regain is seen in 20-30% of the post-bariatric population. More knowledge about the effect of physical activity and eating style on weight change after Roux-en-Y gastric bypass is essential since behaviour can be modified and thereby results improved. The goal of this study is to determine the relationship between weight change, selfreported physical activity and eating style. Methods Weight, physical activity (PA) and eating style (ES) were assessed before surgery and 15, 24, 36 and 48 months after surgery. A linear mixed model was performed to assess the association between the change in PA and ES and percentage total weight loss (% TWL). Results There were 4569 patients included. Preoperative PA and ES were not related to weight change. Change in PA was positively associated with % TWL at 15, 36 and 48 months follow-up. Change in emotional eating was negatively related to % TWL at all follow-up moments. Change in external eating was only negatively related to weight loss at 24 months follow-up. Change in restrained eating was negatively associated with weight loss up to 36 months follow-up. More restrained eating at 36 months follow-up was related to higher weight regain, and more emotional eating at 48 months to 48-month weight regain. Conclusion Preoperative self-reported PA and ES did not predict weight change after RYGB. Being are more physically active and showing less emotional and restrained eating was related to a higher weight loss. Emotional and restrained eating were related to higher weight regain.

There are striking differences regarding body image satisfaction and depressive symptoms when comparing postbariatric patients and without desire for BCS. Body image satisfaction is associated with less depressive symptoms in all postbariatric patients. In patients who desired BCS, body image is one of the mediators of the relationship between percentage total weight loss and depressive symptoms. Therefore, body image should be taken seriously and be part of outcome assessment in postbariatric patients.