Gut Hormone Changes Following Bariatric Surgery Explains Benefits

After weight-loss surgery, a number of changes in gut hormone levels occur that may help explain the appetite reduction, weight loss, and improved glycemic control seen with these procedures.

Dr. Stephen R. Bloom, from Imperial College London, and colleagues assessed changes in various gut hormone levels following Roux-en-Y gastric bypass and jejuno-intestinal bypass in humans and rodents.

Patients who underwent Roux-en-Y gastric bypass had higher postprandial levels of peptide YY (PYY) and glucagon-like-peptide-1 (GLP-1) than did lean and obese controls, which would be expected to increase satiety, the report indicates. In addition, Roux-en-Y gastric bypass patients showed early and exaggerated insulin responses, which might help explain the enhanced glycemic control observed.

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."
Ann Surg 2006;243:108-114.

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FACT:
The C.D.C. has projected that a child found to have Type 2 diabetes at age 10
will see his life shortened by 19 years.