School Lunch, TV Time Linked With Obesity

Among middle school children, the behaviors most often linked with obesity are school lunch consumption and two hours or more of daily TV viewing, according to the University of Michigan Frankel Cardiovascular Center in a study published in Pediatrics.

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 Project Healthy Schools showed girls who drank two servings of milk each day were less likely to be obese and boys who played on a sports team were at a healthier weight.

“Additional work is needed to help us understand the beneficial impact of improving school lunches and decreasing screen time,” says cardiologist and senior study author Elizabeth Jackson, MD, MPH, an assistant professor of internal medicine at the University of Michigan Medical School. “Presumably playing video games or watching TV replaces physical activity.”

Students enrolled in sixth grade at 20 schools from four communities in southeastern Michigan were eligible for participation in this study. The median age was 11.

Obese children 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 with normal weight kids. “Cardiovascular disease doesn’t just start in adulthood, and there may be factors that could help us identify during youth or adolescence who might be at increased risk for developing health problems later on,” Jackson says.

Other studies have linked eating school-provided lunches with obesity, but a major issue with such studies, Jackson says, is the influence of socioeconomic status. Poor children eligible for free or reduced school lunch already may be overweight, considering the link between obesity and lower socioeconomic status. “Although we weren’t able to examine the specific nutritional content of school lunches, previous research suggests school lunches include nutrient-poor and calorie-rich foods,” she says.

The University of Michigan 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. 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 two or more hours per day. The assumption is watching television mediates physical activity, but there were gender differences in how children spent their screen time. Obese girls were more likely than any other group to use a computer. Obese boys reported playing video games more often than normal-weight boys, although the association wasn’t as strong as in other studies.

“We did not find a significant association between time spent playing video games and obesity among boys, which has been observed in other studies,” says study lead author Morgen Govindan, an investigator with the Michigan Cardiovascular Research and Reporting Program at the University of Michigan. “Although we saw a similar trend, the association wasn’t as strong, perhaps due to our smaller sample size.

“Exploring such gender-related differences in a larger group may help in refining the interventions to promote weight loss and prevent obesity among middle school children,” she adds.

Source: University of Michigan Health System