BACKGROUND/AIMS: Improving health-related quality of life (HRQoL) along with decreasing obesity-related morbidity is one of the cornerstones of bariatric surgery. The aim of the study was to investigate how losing weight influences the HRQoL 1 year after gastric bypass and whether HRQoL prior to surgery predicts the amount of weight loss 1 year after gastric bypass. METHODS: One hundred and thirty-nine obese women [median (range): age 45 years (20-71), BMI 44 (29-88)] admitted for gastric bypass were selected prospectively and completed the Nottingham Health Profile (NHP) quality of life questionnaire before and 1 year after surgery. RESULTS: Weight loss 1 year after gastric bypass was significant [-37 kg (9-74), p < 0.001] and led to an improvement of quality of life [NHP total score before surgery 62 (39-76) and after surgery 20 (7-65), p < 0.001]. CONCLUSIONS: HRQoL improves dramatically 1 year after gastric bypass. This HRQoL improvement is not influenced by the amount of weight loss, but rather by the BMI achieved at that time.