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January 15, 2019
School nutrition policies reduce weight gain
At a Glance
- Implementing nutrition policies at middle schools limited unhealthy weight gains in students.
- The effect was strongest in children who started at a healthy weight, highlighting that nutrition policies can be an effective obesity prevention strategy in schools.
Almost one-third of children and adolescents nationwide are overweight or obese. Just like in adults, excess body weight puts kids at risk for diabetes, high blood pressure, and other diseases. Researchers have been testing strategies to help children maintain a healthy weight into adulthood.
Most school districts in the U.S. are required to write wellness policies that set goals for nutrition education and physical activity. However, school districts may lack the expertise and funds to fully implement these policies.
A research team led by Dr. Jeannette Ickovics from the Yale School of Public Health and Dr. Marlene Schwartz from the University of Connecticut Rudd Center for Food Policy and Obesity wanted to see if helping schools implement their existing policies would lead to healthier weights for their students. The team enrolled 12 randomly selected middle schools from a single school district in Connecticut in their study.
Overall, the school populations were diverse: about 47% of kids were Hispanic and 35% were African-American. The researchers assigned schools to four groups: help implementing their nutrition policies; help implementing their physical education policies; help implementing both; or no immediate help.
Assistance with nutrition policies included helping schools choose healthy foods for their cafeterias and providing alternatives to food during classroom celebrations. Interventions to increase physical activity included fitness challenges and integration of exercise into classroom lessons.
Measurements of body mass index (BMI)—a ratio of weight to height—were made each year from fifth through eighth grade. The children also filled out a survey on nutritional and physical activity habits yearly. The study was funded by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and others. Results were published in the January 2019 issue of the American Journal of Preventive Medicine.
Over the three years of the study, implementation of physical activity policies alone did not make a significant difference in students’ BMI. However, implementing nutrition policies—either alone or in combination with physical activity—did help the children maintain their weight. By the third year of the study, students at the schools that implemented nutrition policies had an average BMI increase of less than 1%. In contrast, children at schools that did not implement nutrition policies saw their average BMI rise by about 3 to 4%. That translates to an average of two pounds of extra weight gained each year.
Children at the schools with nutrition policy support also reported eating fewer unhealthy foods and drinking fewer sugar-sweetened beverages.
More than half the students were already overweight or obese at the start of the study. The participants whose weight was in the healthy range were more likely to avoid an increase in BMI during the study than those who started out overweight or obese. This highlights the importance of early prevention.
“This is some of the strongest evidence we have to date that nutrition education and promoting healthy eating behaviors in the classroom and cafeteria can have a meaningful impact on children’s health,” Schwartz says. “These findings can inform how we approach federal wellness policy requirements and implementation in schools to help mitigate childhood obesity.”
—by Sharon Reynolds
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References: Implementing School-Based Policies to Prevent Obesity: Cluster Randomized Trial. Ickovics JR, Duffany KO, Shebl FM, Peters SM, Read MA, Gilstad-Hayden KR, Schwartz MB. Am J Prev Med. 2019 Jan;56(1):e1-e11. doi: 10.1016/j.amepre.2018.08.026. PMID:30573151.
Funding: NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), Centers for Disease Control and Prevention, and Yale-Griffin Prevention Research Center.