The challenge of obesity in childhood. I. Incidence, prevalence, and staging.

The incidence and prevalence of obesity in a school-age cohort and the effect of two different weight-reduction treatment programs were studied over 5 years. The study group received diet instruction and met individually with a dietitian weekly for 16 months, and the control group received only the diet instruction. After 5 years, the students were evaluated by triceps skinfold measurements, a parents' questionnaire, and a structured interview. The incidence of obesity over the 5-year period was 7.8%, or 1.6% per year. The prevalence of obesity increased considerably as students entered adolescence. The overall prevalence of obesity for grades 4, 5, and 6 versus grades 9, 10, and 11 was 9.1% and 14.8%, respectively; the greatest increase occurred between grades 10 and 11. There was no significant change in mean weight index in either the study or the control group at 16 months or at 5 years of follow-up. Individuals in both groups did make successful changes in behavior, and these changes resulted in seemingly permanent reductions in weight. The interviews and questionnaires indicated that family environment and interaction played a role in obesity and its treatment. It was found that obese individuals were easily categorized on the basis of attitudes expressed during interviews and that these " stages" correlated highly with 5-year changes in weight index and triceps skinfold measurements.