Context: Roux-en-Y gastric bypass (RYGB) surgery is an effective long-term intervention for weight
loss maintenance, reducing appetite, and also food reward, via unclear mechanisms.
Objective: To investigate the role of elevated satiety gut hormones after RYGB, we examined food
hedonic-reward responses following their acute post-prandial suppression.
Design: Randomised placebo-controlled double-blind cross-over experimental medicine studies.
Patients: Two groups, over 5 months after RYGB for obesity (n7–11), compared with non-obese
controls (n10), or patients after gastric banding (BAND) surgery (n9).
Intervention: Studies were performed after acute administration of the somatostatin analogue
Octreotide or saline. In one study, patients after RYGB, and non-obese controls, performed a
behavioral progressive ratio task (PRT) for chocolate sweets. In another study, patients after RYGB,
and controls after BAND surgery, performed a functional magnetic resonance imaging (fMRI) food
picture evaluation task.
Main outcome measures: Octreotide increased both appetitive food reward (breakpoint) in the
PRT (n9), and food appeal (n9) and reward system blood oxygen level dependent (BOLD) signal
(n7) in the fMRI task, in the RYGB group, but not in control groups.
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