Long-Term Modulation of Appetitive Hormones and Sweet Cravings After Adjustable Gastric Banding and Roux-en-Y Gastric Bypass

Background Roux-en-Y gastric bypass (RYGB) produces greater weight loss compared with a purely restrictive procedure such as laparoscopic adjustable gastric banding (LAGB). Objective The objective of this study was to quantify changes in hormones that regulate energy homeostasis and appetitive sensations before and after LAGB (n = 18) and RYGB (n = 38) in order to better understand the mechanisms underlying the greater weight loss after RYGB. Methods A standardized test meal was administered prior to surgery, at 6 months, and annually thereafter to year 2 after LAGB and year 4 after RYGB. Blood samples were obtained in the fasted state and 30, 60, 90, and 120 min post-meal. Results Progressive increases in fasting PYY were observed after RYGB together with increases in postprandial area under the curve (AUC) levels that were unchanged after LAGB. GLP-1 AUC increased only after RYGB. There was a weight loss-related increase in fasting ghrelin levels after LAGB that was unchanged 1 year after RYGB despite greater percentage weight loss; ghrelin subsequently increased at years 2-4 post-RYGB. HOMA-IR decreased after both procedures but correlated with weight loss only after LAGB, whereas leptin correlated with weight loss in both groups. Sweet cravings decreased after RYGB. Conclusion A number of weight loss-independent changes in the gut hormonal milieu likely act in concert to promote a decrease in insulin resistance and greater weight loss efficacy after RYGB. A progressive change in hormone levels over time may reflect gut enteroplasticity after RYGB. A decrease in sweet cravings specific to RYGB may further promote superior weight loss outcomes.