Journal Issue: Childhood Obesity Volume 16 Number 1 Spring 2006
School-Based Obesity-Prevention Interventions
Many school-based interventions in recent years have promoted healthful eating and physical activity among children and adolescents, but relatively few interventions have specifically targeted obesity prevention. Several comprehensive reviews have summarized the research analyzing obesity-prevention, nutrition, and physical activity intervention.143 Overall, the findings of studies that targeted eating and physical activity behaviors have been positive. School-based obesity- prevention interventions have also shown some success in changing eating and physical activity behaviors but have been less effective in changing body weight or body fatness.144 A recent report by the Task Force on Community Preventive Services concluded that insufficient evidence existed to determine the effectiveness of combined nutrition and physical activity interventions to prevent or reduce obesity in school settings. The limited number of qualifying studies, for example, report noncomparable outcomes.145
In one such study, T. N. Robinson found that a school-based intervention to decrease television and video viewing reduced the prevalence of obesity among third and fourth graders.146 Planet Health, a school-based intervention to decrease television viewing and increase physical activity and healthful eating among students, decreased obesity among girls but not boys.147 A third intervention, which reduced soft drink consumption in England, lowered the number of overweight and obese children aged seven to eleven.148
Several interventions have changed food environments in schools, reducing the fat content of school lunches and modifying the prices of fruits and vegetables in the school cafeteria and in vending machines.149 They have shown that the availability, promotion, and pricing of foods in schools can be changed to support more healthful food choices. Interventions are just beginning to target the availability of competitive foods and beverages. Little research has been done on the effects of school, district, or state policy changes regarding the school food environment or changes in student dietary outcomes or in body mass indexes.
Studies have also shown that school PE classes can be changed to make them much more active and increase the time spent in PE and in moderate to vigorous activity.150 One recent analysis found that an extra hour of PE per week in first grade (compared with time spent in PE in kindergarten) lowered BMI in girls who had been overweight or at risk for overweight in kindergarten.151 No effect was seen in boys. Interventions to increase energy expenditure through increased physical activity and decreased consumption of high-calorie, low-nutrition foods offer promising strategies for preventing obesity.
The few existing school-based obesity-prevention studies suggest that interventions hold promise.152 For future studies, researchers should strengthen interventions and should target the school environment, the home environment, and student and parent behaviors.153 Interventions could modify the home environment by installing devices to monitor television time or by increasing the availability of healthful foods and limiting energy-dense, low-nutrition foods. School environment changes could include more frequent required PE classes, more interesting and fun physical education choices, and school-wide guidelines about food and beverage availability and sales.154
Research can also help reveal whether specific forms of interventions have different effects on children of different age, gender, or ethnic groups. For example, targeting particular behaviors may be more successful with one age group than with another. Younger children may respond better to reducing television viewing while adolescents may benefit from more structured and diverse PE opportunities. Changing Ã la carte and vending machine food and beverage availability may be more effective for high school students than for elementary school students. More research is also needed to identify obesity prevention's most potent behavioral targets, such as limiting screen time, sugar-sweetened beverages, and portion sizes.