Middle school students who buy lunch at school are more likely to be obese than students who bring lunch from home.
Obese sixth graders pack on the pounds in much the same manner as their adult counterparts — too much TV, poor dietary habits, and too little physical activity.
And school lunches appear to be a major factor in those poor dietary habits as kids who buy lunch at school had about a 30 percent greater risk of obesity than kids who brownbag it.
That finding emerged from a University of Michigan study of more than 1,000 sixth graders. The results were reported recently in the American Heart Journal.
Other factors linked to obesity were spending two or more hours in front of a TV or video game within the past day, which increased the risk of obesity by about 19 percent compared with sixth graders who watched less TV.
Kids who regularly engaged in moderate physical activity — such as a 20-minute gym class five days a week — reduced the risk of obesity by an average of 11 percent compared with couch potatoes.
The unhealthy behaviors translated into an unfavorable metabolic profile, including lipids, blood pressure, blood glucose, and heart rate.
“Opportunities to improve child health should emphasize programs that increase physical activity, reduce recreational screen time, and improve nutritional value of school lunches,” Dr. Kim A. Eagle, of the University of Michigan in Ann Arbor, and co-authors wrote in conclusion.
“Whether genetic or not, childhood obesity can be attacked.”
Current theories about the origin of obesity have generally placed most of the blame for the condition on either behavioral factors or heredity and genetically determined susceptibility.
In an effort to inform on the issue, the investigators developed a school-based intervention to improve the health status of middle-school students in several towns in the southeast part of Michigan.
The intervention had built-in research opportunities to examine possible associations between the students’ physical activity, food intake, physiologic measures, and body mass index (BMI).
“We reasoned that if dietary patterns and physical activity were similar in obese and non-obese students, this would argue for a stronger genetic basis for obesity in our subjects,” the authors wrote in the introduction to their report.
“We also hypothesized that obesity before adolescence is associated with physiologic characteristics, including blood pressure, fitness, serum glucose, and serum lipids,” the authors added.
The program, called Project Healthy Schools, has five principal goals: increase intake of fruits and vegetables, reduce consumption of fatty foods and fast food, reduce consumption of sugar-containing beverages, increase physical activity, and reduce sedentary behaviors.
The intervention included a variety of educational materials and modification of environmental factors in the schools, such as school lunches, items stocked in campus vending machines, and substitution or replacement of sugar-containing sodas with bottled water whenever possible.
Comparison of self-reported diet and beverage behaviors identified three significant differences. Obese children were:
- Less likely to have consumed milk within the previous 24 hours 83 percent versus 90 percent.
- More likely to consume school lunches on most days, 45 percent versus 34 percent.
- More likely to consume regular sodas/soft drinks daily or almost daily 40 percent versus 30 percent.
Analysis of physical activity showed that obese students were significantly less likely to have exercised for at least 20 minutes a day for five days in the previous week, 46 percent versus 56 percent. They were also less likely to participate in school or organized sports.
The study was supported by the University of Michigan, the Thompson Foundation, the Hewlett Foundation, the Mardigian Foundation, and the Robert C. Atkins Foundation.