Obesity Intervention Study Produces Mixed Results

The HEALTHY program, a three-year government-funded intervention in middle schools that was designed to lower overall rates of overweight and obesity among students, has produced mixed results.

The National Institutes of Health, which designed the intervention, hoped that the target school students would show significantly lower rates of obesity and overweight than students in comparison schools where no intervention took place. By the end of the three-year study, however, both target and comparison schools saw the same 4 percent decrease in their rates of overweight and obesity.

In short, there was no evidence that the NIH program had any effect on students. Although program elements included increased, more intense physical education, changes in onsite food services, and classroom sessions that encouraged behavioral changes, they apparently made no difference compared with conventional instruction.

However, the target school students with high body mass indexes-85th percentile or higher-who participated in the intervention had 21 percent lower odds of becoming obese than students with similar BMIs at the comparison schools. (Overweight is defined as a BMI that puts children in the 85th to 94th percentile of weight for their sex and age. Obesity is defined as a BMI in the 95th percentile or higher.)

The NIH says that while nationally about one-third of middle school students are in the 85th percentile or higher, one half of the sixth graders in the HEALTHY study were at that level or higher.

NIH spokesmen said that the almost identical drop between target and comparison schools in overall rates of overweight and obesity was unexpected. The NIH plans to look into reasons why schools without the HEALTHY program performed as well as the ones with it. One possible explanation a spokesman offered was that the comparison schools, already alerted to the dangers of obesity, independently put into place program changes designed to lower students’ weights.  

The HEALTHY program involved 4,600 students at 42 middle schools (sixth through eighth grades) across the country. Schools were randomly assigned status as a target/program school or a comparison school.

Because of the high rate of type two diabetes among ethnic minority and low-income people, the NIH conducted the study in schools with high enrollments of minority (54 percent Hispanic and 18 percent African American) and low-income students (75 percent of the students were eligible to receive partially or fully taxpayer-subsidized meals).

The specifics of the HEALTHY program included:

  • Offering lower-fat, higher-fiber foods in the cafeteria, including more fruits and vegetables, and drink selections based on water, low-fat milk, or beverages with no added sugar
  • Providing longer, more intense physical education sessions, designed to achieve heart rates of at least 130 beats per minute during periods of greatest intensity
  • Instituting classroom activities and instruction intended to educate and motivate students to adopt long-term behaviors that promote health and weight control.


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