By contrast, patients who lost a comparable amount of weight through gastric banding did not show these hormonal changes, the authors point out. No significant differences in leptin, ghrelin, or pancreatic polypeptide were seen between Roux-en-Y gastric bypass patients and those treated with gastric banding.

In rats, jejuno-intestinal bypass seemed to cause similar changes in PYY and GLP-1 as Roux-en-Y gastric bypass did in humans, the report indicates. Further testing showed that treating the animals with PYY decreased food intake, while blocking endogenous PYY increased intake.

"Following bypass surgery, it is likely that multiple mechanisms act in concert to achieve sustainable weight loss," the investigators note. "Replicating the hormonal milieu that arises as a consequence of gastric bypass surgery, through pharmacologic means holds promise for future medical intervention in morbid obesity."