January 26, 2005

Genes May Influence Weight Gain in Adults

Study finds genetics account for about 50% of change in body mass index

HealthDayNews -- Your genes may be one reason your jeans are getting tighter, says a Saint Louis University School of Public Health study that found genetics can play a role in some peoples' weight problems.

"About 50 percent of adult-onset weight change remains genetic," principal investigator James C. Romeis, a professor of health services research, said in a prepared statement.

He studied nearly 4,000 sets of male twins who served in the military during the Vietnam War. Some of them were identical twins who shared the same genes and others were fraternal twins who shared half their genes.

The study found that genes account for about 50 percent of the change in body mass index, a ratio of weight to height. Exercise and diet are among the other factors that influence the other 50 percent.

For someone with genes that predispose them to being heavy, weight loss can be more difficult and require extra effort, the study found.

"We're not acknowledging the strength of genetic factors in our weight-loss strategies," Romeis said. "You've got this genetic thing working against you that helps to explain why you're so heavy, and why you may fail diets and weight-loss programs."

A sedentary, overindulgent lifestyle can be a problem for people with a genetic predisposition for being fat, he said.

"While genetic vulnerability has probably not changed during the past few years, environments have, thus allowing for the genetic vulnerability to be expressed as what appears to be an alarming rate of increase," Romeis said.

The study appeared in a recent issue of Twin Research.

More information

Saint Louis University School of Public Health

The U.S. Centers for Disease Control and Prevention has more about factors that contribute to obesity.