School lunch, TV time linked with childhood obesity

August 14, 2013

A study published in Pediatrics shows that among middle-school children, the behaviors most often linked with obesity are school lunch consumption and two hours or more of daily TV viewing. In addition, while some habits were the same for all overweight and obese children, the study found some gender differences in the habits influencing body weight.

Data from 1,714 sixth grade students enrolled in 20 Project Healthy Schools from four communities in southeastern Michigan were compared by using health behaviors and physiologic markers. The median age was 11. The Project Healthy Schools program is designed to teach sixth graders heart-healthy lifestyles including eating more fruits and vegetables, making better beverage choices, engaging in 150 min of exercise per week, eating less fast food and less fatty foods, plus reducing time spent in front of computer and video game screens.

The researchers found that non-obese students (both boys and girls) showed significantly healthier physiologic parameters compared with their obese counterparts. Obese boys and girls had poor cardiovascular profiles with lower HDL-cholesterol, higher triglycerides, higher blood pressure, and higher heart rate recovery—indicating a lower level of fitness—compared to normal weight kids.

Two behaviors independently correlated with obesity in both boys and girls: regularly eating school lunches and watching 2+ hrs of television per day. It should be noted that the researchers did not examine the nutritional content of the school lunches. The researchers hypothesized that poor children eligible for free or reduced school lunch may already be overweight, considering the link between obesity and lower socioeconomic status.

The study adds a new element in the fight to reduce childhood obesity by providing a real-world view of the gender differences in obesity risk factors. Girls in general were significantly less likely to report being physically active. One possible explanation, authors say, is the potential for activities such as dance or cheerleading not considered by children to be sports, and such activities are more prevalent among girls.

Milk consumption seemed to protect girls from obesity, but made no difference for boys. A possible explanation would be a reduction in sugary drinks, which girls replaced with milk.

In the study, 61% of obese boys and 63% of obese girls reported watching television for 2+ hrs a day. The assumption is watching television mediates physical activity, but there were gender differences in how children spent their so-called “screen time.”

Abstract