Decrease of 'Hunger Hormone' after Obesity Surgery

According to researchers at the Puget Sound Health Care System, obese adults who undergo 'stomach stapling' have much lower levels of a recently discovered 'hunger hormone' than either normal-weight people or those who lose weight by dieting.

Dr. David E. Cumming from the Puget Sound Health Care System in Seattle, suggested that drugs that suppress the hormone called ghrelin could curb appetite and may cut rates of obesity and related problems such as type 2 diabetes and other chronic disorders. He felt that, obesity is a huge problem and insights into the mechanisms of body weight regulation giving rise to treatments are very important," he said.

Ghrelin, a hormone produced by the stomach, is named for the Hindi word for growth. Past studies have shown it rises just before eating and falls after a meal and can make people so ravenous they eat nearly a third more food than usual. But it was not clear what happened to levels after dieting or in people who had gastric bypass surgery.

A team of investigators measured levels of ghrelin in the blood of 10 obese individuals before and after a 5-month weight loss program, in 6 adults who had lost weight after gastric bypass surgery, and in 10 normal-weight adults.

Patients had undergone a type of gastric surgery known as Roux-en-Y, in which a surgeon creates a small pouch in the stomach and also bypasses a portion of the small intestine. Afterwards, patients tend to eat less--and lose weight--because they feel full on less food.

But the surgery also appears to inhibit the production of ghrelin, thereby contributing to long-term weight loss. The finding may help explain why people undergoing surgery feel less hungry between meals, even though their intake of food has dropped dramatically.

After surgery, the patients had lower levels of the hormone compared with both normal-weight people and obese people who lost weight by dieting. For example, dieters who had a 30% weight loss--the equivalent of 34 pounds for a 200-pound woman--had a 24% increase in ghrelin levels compared with their pre-diet levels. In contrast, people who underwent surgery had ghrelin levels 80% lower than normal-weight people, even though they had a 30% weight loss.

Hormone levels also rose sharply before meals and declined after eating among obese dieters and normal-weight adults but remained steady in individuals who had surgery. Dr. Jeffrey S. Flier from Medical Center in Boston, Massachusetts notes that research into whether these drugs will mimic the effects of gastric bypass surgery or result in unexpected medical consequences is needed.

It is also unclear how gastric bypass surgery leads to a reduction in ghrelin levels. Nonetheless, the findings indicate that the hormone contributes to hunger and plays a key role in the long-term regulation of body weight, the study authors note. They concluded that their finding showed significant reduction of ghrelin levels after gastric bypass and thereby suggests that suppression of ghrelin can be studied as a potential mechanism by which this procedure causes weight loss.