Weight-loss surgery and hormone changes

Weight-loss surgery works not just by restricting the amount of food absorbed by the body, but also, partially, by causing hormone changes that reduce appetite and improve sugar metabolism. If these changes can be mimicked with drugs, it could lead to new treatments for severe obesity. Researchers from the Imperial College London, UK, assessed how stomach or intestinal bypass operations affected hormones secreted by the gut in humans and in rodents. Patients who underwent stomach bypass had increased levels of two hormones, Peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), which would be expected to produce sensations of fullness after eating. In addition, these patients had changes in their insulin response that would lead to improved blood sugar levels. In contrast, patients who lost a comparable amount of weight through gastric banding, a procedure in which the size of the stomach is restricted but it's not actually bypassed, did not show these hormonal changes. In rats, intestinal bypass seemed to cause similar changes in PYY and GLP-1 as did stomach bypass did in humans. Following bypass surgery, it is likely that multiple mechanisms act in concert to achieve sustainable weight loss, the researchers noted. Replicating the hormonal milieu that arises as a consequence of stomach bypass surgery with medications holds promise as a treatment for obesity in the future.