Overweight boys had lower levels of an appetite-decreasing hormone in response to food than healthy-weight adolescents did, according to a Canadian study being presented Saturday, June 2, at The Endocrine Society’s 89th Annual Meeting in Toronto.

This finding raises the possibility that insufficiency of the naturally occurring hormone, glucagon-like-peptide 1 (GLP-1), plays a role in being overweight, said the study author, Dr. Jean-Pierre Chanoine. A pediatric endocrinologist at British Columbia’s Children’s Hospital in Vancouver, Chanoine explained that GLP-1 is one of many hormones in the body that control appetite. It normally increases after a meal and signals fullness (satiety) to the brain.

The author wanted to know whether exercise affects this appetite-regulating hormone in young people, because exercise is a frequently recommended treatment of being overweight. Chanoine measured GLP-1 response to a liquid meal in 34 male adolescents (average age, 15) before and after five days of aerobic exercise lasting an hour a day. He limited the duration of exercise to five days, so no weight loss would occur, which would have made it difficult to isolate the hormonal effect of exercise. Seventeen of the study subjects were of normal weight, and the other 17 were overweight.

Overweight subjects had significantly lower blood levels of the GLP-1 hormonal signal for fullness at the beginning of the study. In both overweight and healthy-weight adolescents, the acute GLP-1 response to the liquid test meal (change between 0 and 30 minutes) was greater after exercise than before exercise.

The data show that exercise has positive effects on GLP-1concentrations, according to Chanoine. Some investigators have suggested that physical activity increases hunger.

“In theory, this is good news for overweight adolescents who increase physical activity,” Chanoine said. “However, it remains to be demonstrated whether these hormonal changes actually translate to decreased appetite and decreased food intake.”

###