Decreased energy density and changes in food selection following Roux-en-Y gastric bypass

BACKGROUND/OBJECTIVES: The main objective was to test the hypothesis that dietary energy density (DED) decreases after Roux-en-Y gastric bypass (gastric bypass). SUBJECTS/METHODS: A total of 43 patients (31 women and 12 men) aged 43 (s.d. 10) years, with body mass index (BMI) 44.3 kg/m(2) (4.9), were assessed preoperatively at 6 weeks and 1 and 2 years after gastric bypass. Self-reported energy intake (El), food weight (FIN) and food choice were assessed using a dietary questionnaire. DED was calculated by dividing EI by FW (kcal/g). Number of dropouts was 4 of 203 visits. RESULTS: Percent weight loss (%WL) was 13.5% at 6 weeks, 30.7% at 1 year and 31.8% at 2 years post surgery (P<0.001 for all). EI decreased from 2990 to 1774, 2131 and 2425 kcal after 6 weeks and 1 and 2 years postoperatively, respectively (P<0.001 at all time points). FW changed from 2844 to 1870 g/day at 6 weeks (P<0.001) and 2416 g/day after 1 year (P<0.05), but was not significantly different from baseline 2 years postoperatively (2602 g/day, P=0.105). DED decreased from 1.07 to 0.78 kcal/g at 6 weeks (P<0.001) and 0.90 kcal/g (P<0.001) and 0.96 kcal/g (P=0.001) after 1 and 2 years, respectively. All statistical comparisons were made from baseline. There was no correlation between changes in DED and %WL, neither after 1 year (r=-0.215; P=0.183) nor after 2 years (r=-0.046; P=0.775) post surgery. CONCLUSIONS: Besides substantial reduction in EI and large variation in FW, patients reported decreased DED over 2 years following gastric bypass. Despite lack of association between the reduction in DED and percentage weight loss, changes in food choice were overall nutritionally beneficial. European Journal of Clinical Nutrition (2013) 67, 168-173; doi:10.1038/ejcn2012.208; published online 9 January 2013