Roux-en-Y gastric bypass (RYGB) has greater efficacy for weight loss in obese patients than gastric banding (BAND) surgery.
Dr Tony Goldstone and colleagues from the United Kingdom hypothesized that this may result from different effects on food hedonics via physiological changes secondary to distinct gut anatomy manipulations.
The team used functional MRI, eating behaviour and hormonal phenotyping to compare body mass index (BMI)-matched unoperated controls and patients after RYGB and BAND surgery for obesity.
Obese patients after RYGB had lower brain-hedonic responses to food than patients after BAND surgery.
|RYGB patients had lower activation in brain reward systems|
The team noted that RYGB patients had lower activation than BAND patients in brain reward systems, particularly to high-calorie foods, including the orbitofrontal cortex, amygdala, caudate nucleus, nucleus accumbens and hippocampus.
The researchers found that this was associated with lower palatability and appeal of high-calorie foods and healthier eating behavior, including less fat intake, in RYGB compared with BAND patients and/or BMI-matched unoperated controls.
These differences were not explicable by differences in hunger or psychological traits between the surgical groups, but anorexigenic plasma gut hormones (GLP-1 and PYY), plasma bile acids and symptoms of dumping syndrome were increased in RYGB patients.
Dr Goldstone and team conclude, "The identification of these differences in food hedonic responses as a result of altered gut anatomy/physiology provides a novel explanation for the more favorable long-term weight loss seen after RYGB than after BAND surgery, highlighting the importance of the gut–brain axis in the control of reward-based eating behavior."