Study: Appetite-Increasing Hormone Ghrelin May Frustrate Dieters

For most dieters, keeping off the pounds after they reach their weight goal seems almost impossible, and researchers at the University of Washington now say a hormone secreted by the stomach may be to blame.

Levels of the appetite-increasing hormone ghrelin rise dramatically in dieters after they lose weight, the researchers said, but drop significantly in patients who have undergone gastric-bypass surgery.

Ghrelin secretion peaks just before each meal and declines afterwards, according to the study. The hormone not only acts on appetite, it slows metabolism and reduces the burning of fat in the body.

Investigators followed 13 obese subjects who dieted and lost 17 percent of their body weight over a six-month period. The dieters' levels of ghrelin after weight loss were significantly higher throughout the day, possibly the body's attempt to regain the lost weight. The more weight a patient lost, the higher the increase in their ghrelin levels.

Researchers speculate that the hormone was once used by the body as a protection against unhealthy weight loss in a harsh environment where food supplies were not always available.

The study also included five patients who had undergone gastric-bypass surgery who were found to have almost no level of ghrelin production afterwards. Gastric-bypass patients experience a significant disinterest in food after their surgery.

Compared to obese controls who did not have stomach surgery, the gastric-bypass patients had a 72 percent lower ghrelin production and they had a 77 percent lower ghrelin production than normal weight controls. Patients who have had the obesity surgery do not appear to suffer ill effects from a reduction in ghrelin production, according to the researchers.

A drug that could block the action of ghrelin could become a promising weapon in the fight against obesity. Ghrelin may also prove helpful as a therapy to help patients who lose excessive weight with diseases such as cancer and AIDS.

Other sources: New England Journal of Medicine, Washington Post