Factors influencing energy intake and body weight loss after gastric bypass

Objective The gastric bypass-induced quantitative and qualitative modifications of energy intake (En In, kcal/day) and their impact on body weight (bw) loss were evaluated. The factors influencing energy intake and body weight loss were also investigated.Design Longitudinal study.Setting University Hospital of Geneva.Subjects Fifty obese women undergoing a Roux-en-Y gastric bypass.Results The reduction of EnIn was significantly related to bw loss expressed either in kg or as percentage correction of excess bw (PConclusions Gastric bypass-induced body weight loss is mainly due to the reduction of EnIn, whereas the qualitative modifications of the diet do not play a role. Younger subjects have a greater capacity to reduce EnIn and, therefore, lose more weight. Pre-operative high degree of obesity leads to a larger weight reduction, probably because of a greater energy deficit.