Changes in Gastrointestinal Hormones and Leptin After Roux‐en‐Y Gastric Bypass Surgery

Abstract

Background: Roux‐en‐Y gastric bypass (RYGB) imparts long‐term weight loss, the mechanisms for which are not well understood. Changes in leptin and gastrointestinal (GI) hormones, including glucagon‐like peptide 1 (GLP‐1), peptide YY (PYY), and ghrelin, may contribute to the relative success of RYGB compared with conventional weight loss methods. This study evaluated changes in GI hormones and leptin post‐RYGB. The study also evaluated whether GI hormones differed after a short‐term dose of protein or fat. Methods: GLP‐1, PYY, ghrelin, and leptin were assessed in 16 women before RYGB and up to 1 year after RYGB. Plasma was collected before and at several times after a short‐term equicaloric dose of protein or fat. Results: GLP‐1 area under the curve (AUC) increased at week 6 and 1 year in the fat beverage (FAT‐BEV) group compared with baseline. PYY AUC remained elevated at 1 year in the FAT‐BEV group. Ghrelin AUC decreased at week 2, week 6, and 1 year in the protein beverage (PRO‐BEV) group compared with baseline. Ghrelin AUC was lower in the PRO‐BEV group compared with the FAT‐BEV group at week 6. Fasted leptin decreased at all visits in both groups and was lower in the FAT‐BEV group compared with the PRO‐BEV group at 1 year. Conclusions: Changes from baseline were evident for all GI hormones and leptin; some differences were evident soon after surgery (ghrelin, leptin), whereas others were maintained long term (GLP‐1, PYY, ghrelin, leptin). In response to a short‐term stimulus, protein suppressed ghrelin and fat potently stimulated GLP‐1 and PYY. Future work in this area is warranted.