Feeding the Obesity Monster

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

Check-ups of 1,003 Michigan sixth-graders in a school-based health program showed that obese children 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, which are published in the American Heart Journal, suggest that unhealthy habits are feeding the childhood obesity trend.

“For the extremely overweight child, genetic screening may be a consideration,” said study senior author Kim A. Eagle, MD, a cardiologist and a director of the University of Michigan Cardiovascular Center, in a press release. “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.”

The prevalence of obesity among US children ages 6 to 11 has increased from 6.5% in 1980 to 19.6% in 2008.

Children involved in the study participate in Project Healthy Schools, a school-based program supported by communities and the University of Michigan 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.

University of Michigan researchers found that 58% of obese children had watched two hours of TV in the previous day, compared to 41% of non-obese children, and that 45% of obese students always ate school lunch, but only 34% 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,” said study first author Taylor Eagle.

In the University of Michigan study, 15% of the middle school students were obese, but nearly all, whether overweight or not, reported unhealthy habits.

More than 30% 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% who are already obese,” said study co-author Elizabeth Jackson, MD, assistant professor of internal medicine at the University of Michigan Cardiovascular Center.