BACKGROUND:

An estimated 25-40 percent of United States pre-adolescents and adolescents are obese. Higher rates have been noted among minority youth. Onset of obesity in late childhood and early adolescence is associated with increased risks of "tracking" of obesity into adulthood, subsequent obesity-related morbidity and mortality, and obesity- related psychosocial morbidity. However, there is limited ability to accurately identify those children who will become obese adults and those who will suffer obesity-related morbidities, Existing treatments for child and adolescent obesity have yielded modest, unsustained effects, and single-component prevention interventions have been relatively ineffective.

DESIGN NARRATIVE:

The intervention model was derived from principles of Bandura's social cognitive theory, and included activities in the school, and the home, and a clinically oriented component for high-risk children. The school component included: a computer-based classroom curriculum; a physical education curriculum; and a school lunch intervention. The home component included correspondence materials and a videotape for parents. Children identified as "high risk" were eligible to enroll in an intensive intervention. In addition, several innovative approaches were included: interventions to influence food preferences and television viewing, interventions promoting health advocacy, and computer-assisted instruction.

An "efficacy trial" evaluated the three-year intervention in a cohort of approximately 1200 3rd graders, in 14 ethnically diverse elementary schools, with follow-up in the 6th grade. 7 schools were randomly assigned to the comprehensive intervention, and 7 schools received an attention-placebo classroom curriculum. Anthropometric measures and assessments of food preferences, cardio-respiratory fitness and self-reported behavior, attitudes and knowledge occurred every six months. Parent interviews occurred annually. Although a careful assessment of effects on parents and the schools was conducted, the crucial question was whether the overall intervention had an impact on student adiposity and behaviors.

The primary objective was to significantly reduce the prevalence of obesity, compared to controls, at the end of the three year intervention. Secondary objectives included maintenance of effects at 6-month follow-up, reducing obesity among high-risk children, improving cardio-respiratory fitness, increasing physical activity, decreasing sedentary activity, reducing the prevalence of unhealthful weight control methods, and improving knowledge, attitudes and perceived self-efficacy regarding the adoption of healthful behaviors. In addition, the investigators identified personal, behavioral and environmental (including family) factors prospectively associated with development of obesity, maintenance of normal weight, weight reduction among overweight children and obesity-related behaviors. Finally, they examined longitudinal changes in height, weight, body mass index (BMI), triceps skin fold thickness, and waist and hip circumferences in girls and boys 8 - 12 years of age, with respect to stages of pubertal development.