The pediatric obesity epidemic: causes and controversies.

Obesity in children and adolescents has reached alarming proportions in the United States. Nutritional surveys do not indicate a significant increase in caloric intake in children and adolescents over the last 3 decades, although caloric intake has increased recently in adolescent females. Dietary fat has also been falling. There is no conclusive evidence linking physical inactivity to the obesity epidemic, and longitudinal studies indicate that physical inactivity may be the result of obesity rather than its cause. Hence, attention should be focused on dietary carbohydrate. Carbohydrate intake has increased as a result of the decrease in dietary fat. Indirect evidence also indicates that the quality of carbohydrate has been changing, so that American children are eating more carbohydrates with a higher glycemic index. It is proposed that high-glycemic-index diets lead to excessive weight gain as a consequence of postprandial hyperinsulinemia. Low-glycemic-index diets lower postprandial insulin levels and insulin resistance. It seems likely that diets restricted in sweetened sodas and noncitrus juices and containing ample whole grains, vegetables, and fruit could have a major impact on the prevalence of pediatric obesity.