Gastrointestinal Hormones and Weight Loss Maintenance Following Roux-en-Y Gastric Bypass

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Factors underlying variable weight loss (WL) after Roux-en-Y gastric bypass (RYGB) are poorly understood.


Our objective was to gain insight on the role of gastrointestinal hormones on poor WL maintenance (P-WLM) following RYGB.

Design and Patients:

First, glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and ghrelin responses to a standardized mixed liquid meal (SMLM) were compared between subjects with good WL (G-WL, n = 32) or P-WLM (n = 22). Second, we evaluated food intake (FI) following blockade of gut hormonal secretion in G-WL (n = 23) or P-WLM (n = 19) subjects. Finally, the impact of dietary-induced WL on the hormonal response in subjects with P-WLM (n = 14) was assessed.


This study was undertaken in a tertiary hospital.

Main Outcome Measures:

In studies 1 and 3, the outcomes measures were the areas under the curve of gut hormones following a SMLM; in study 2, FI following subcutaneous injection of saline or octreotide were evaluated.


P-WLM associated a blunted GLP-1 (P = .044) and PYY (P = .001) responses and lesser suppression of ghrelin (P = .032) following the SMLM challenge. On saline day, FI in the G-WL (393 ± 143 kcal) group was less than in the P-WLM (519 ± 143 Kcal; P = .014) group. Octreotide injection resulted in enlarged FI in both groups (G-WL: 579 ± 248 kcal, P = .014; P-WLM: 798 ± 284 Kcal, P = .036), but the difference in FI between groups remained (P < .001). In subjects with P-WLM, dietary-induced WL resulted in larger ghrelin suppression (P = .046), but no change in the GLP-1 or PYY responses.


Our data show gastrointestinal hormones play a role in the control of FI following RYGB, but do not support that changes in GLP-1, PYY, or ghrelin play a major role as determinants of P-WLM after this type of surgery.

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