Weight-loss surgery linked to hormone changes

NEW YORK (Reuters Health) – Weight-loss surgery works not
just by restricting the amount of food absorbed by the body, it
seems. In part, at least, it leads to weight loss by causing
hormone changes that reduce appetite and improve sugar
metabolism, new research suggests.

If these changes can be mimicked with drugs, it could lead
to new treatments for severe obesity, the researchers note.

As reported in the Annals of Surgery, Dr. Stephen R. Bloom,
from Imperial College London, and colleagues 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, PYY and GLP-1, which would be expected to
produce sensations of fullness after eating, the report
indicates. In addition, these patients had changes in their
insulin response that would lead to improved blood sugar
levels.

By 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, the authors point out.

In rats, intestinal bypass seemed to cause similar changes
in PYY and GLP-1 as did stomach bypass did in humans, the
report indicates.

“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 (stomach) bypass surgery” with
medications holds promise as a treatment for obesity in the
future.

SOURCE: Annals of Surgery, January 2006.