Bariatric surgery is the most effective weight loss therapy, and recently laparoscopic sleeve gastrectomy (LSG) is gaining popularity worldwide. On the other hand, patients undergoing bariatric surgery have a high prevalence of mental disorders. A Japanese nationwide survey reported high prevalence of mental disorders in patients with low percent total weight loss (%TWL) and also in those with high %TWL. The aim of this study was to investigate the relationship of 1-year %TWL with background mental health status, 3-year outcomes, and nutrition intake in Japanese patients after LSG.