Lifestyle more closely linked with childhood obesity, than genetics

University of Michigan Cardiovascular CenterFeb 1 2011

Are some children genetically tuned to be overweight, or is lifestyle to blame for childhood obesity?

Check-ups of 1,003 Michigan 6th graders in a school-based health program showed children who are obese were more likely to consume school lunch instead of a packed lunch from home and spend two hours a day watching TV or playing a video game.

The results were compiled by the University of Michigan Cardiovascular Center and suggests unhealthy habits are feeding the childhood obesity trend.

"For the extremely overweight child, genetic screening may be a consideration," says study senior author Kim A. Eagle, M.D., a cardiologist and a director of the U-M Cardiovascular Center. "For the rest, increasing physical activity, reducing recreational screen time and improving the nutritional value of school lunches offers great promise to begin a reversal of current childhood obesity trends."

President Obama recently signed the Healthy, Hunger-Free Kids Act of 2010 to create healthier school menus for the 31 million children in the United States who eat lunch through school programs.

The act is designed to improve nutrition by reducing salt, fat and sugar in school meals and reduce childhood obesity which has tripled in the U.S. in the past 30 years.

The prevalence of obesity among U.S. children ages 6 to 11 has increased from 6.5 percent in 1980 to 19.6 percent in 2008.

Children involved in the study participate in Project Healthy Schools, school-based program supported by communities and the U-M Health System to teach middle school students about healthy lifestyles, in hopes of reducing their future risk of cardiovascular disease and diabetes.

Project Healthy Schools is available at 13 Michigan middle schools and is one of the few school-based programs to show sustained benefits in reducing cholesterol and high blood pressure among participants.

The U-M study was published in the American Heart Journal.

U-M researchers found that 58 percent of obese children had watched two hours of TV in the previous day, compared to 41 percent of non-obese children. Forty-five percent of obese students always ate school lunch, but only 34 percent of non-obese students ate school lunch.

Significantly fewer obese kids exercised regularly, took physical education classes, or were a member of a sports team.

Because the eating and exercise patterns of obese children were so different than their normal weight peers, researchers concluded that lifestyle was more closely linked with childhood obesity, than genetics.

New evidence has emerged showing a leptin deficiency, a genetic mutation in the hormone that controls hunger, may cause a person to overeat.

"If diets and physical activity were similar in obese and non-obese students this would argue for a stronger genetic basis for obesity in children," says study first author Taylor Eagle.

In the U-M study, 15 percent of the middle school students were obese, but nearly all, whether overweight or not, reported unhealthy habits.

More than 30 percent had consumed regular soda the previous day, and less than half remembered eating two portions of fruits and vegetables within the past 24 hours. Only one-third of students said they exercised for 30 minutes for five days in the previous week.

"It's clear that opportunities to improve health abound for the majority of our students, not just the 15 percent who are already obese," says study co-author Elizabeth Jackson, M.D., assistant professor of internal medicine at the U-M Cardiovascular Center.