The post-prandial pattern of gut hormones is related to magnitude of weight-loss following gastric bypass surgery: a case-control study.

Background: The mechanisms of weight loss after gastric bypass, including the role of gastric hormones, are still not completely understood. While postprandial releases of peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) increase post-surgery and ghrelin usually is reduced, their relationship to the magnitude of the weight loss is still obscure. We explored if differing weight loss after Roux Y gastric bypass (RYGB) in morbidly obese were associated with differing postprandial hormonal release.

Methods: We compared patients with large (> 40%) or moderate (< 25%) weight loss three years following RYGP surgery, and an obese control group scheduled for RYGB (six in each group). A 300 kcal mixed meal test was given with blood sampling before and thereafter at 30-min intervals in 180 min. Peak and incremental area under the curve (iAUC) were calculated to characterize postprandial responses.

Results: Early postprandial GLP-1 response were significantly higher in the RYGB groups than in the controls, and highest in those with largest weight loss. Postprandial PYY response were also greater for the two RYGB groups vs. controls, but interestingly the controls had higher baseline values. Ghrelin, from similar baseline, was only suppressed in those with the largest weight loss, with close to no reduction in those with modest weight loss or controls.

Conclusions: These results support the hypothesis that the magnitude of weight loss after RYGB surgery might be associated with differing patterns of postprandial responses in GLP-1 and ghrelin, but not PYY. Larger studies are warranted.