Neural Response to Eating and Weight Status

We hypothesize that RYGB-treated patients will exhibit greater reductions (from baseline) in BOLD response in areas associated with homeostatic and hedonic eating than will both LAGB/LSG and control patients. We also expect that LAGB/LSG patients (as a result of hormonal changes occurring with weight loss) will display greater increases in BOLD response to images of highly palatable foods than will extremely obese controls. We expect that RYGB-treated patients will show larger increases (relative to baseline) in postprandial GLP-1 and PYY3-36 than the LAGB/LSG and obese control groups. We will also compare changes in ghrelin in the three groups. We predict that patients who undergo RYGB will have greater reductions in ghrelin than will control subjects. We expect that RYGB-treated patients will demonstrate greater postprandial changes (relative to baseline) in brain activity in the homeostatic and hedonic feeding areas (suggesting normalization of satiety and of neural processing of food reward) than will patients who undergo LAGB/LSG or who do not seek weight loss.