METABOLIC IMPACT OF OBESITY IN CHILDHOOD

The prevalence of obesity is increasing alarmingly among children and adolescents in the United States. Recent data from the National Health and Nutrition Examination Survey (NHANES III) indicate that approximately 20% of children and adolescents are overweight as defined by a body mass index greater than the 85th percentile.30, 58 This secular trend in childhood obesity parallels a concurrent increase in obesity among adults.³⁵

Obesity is a disorder of energy metabolism. Subtle chronic imbalance between energy intake and energy expenditure leads to storage of excess energy in the form of triglycerides in adipose tissue. The rise in both adult and childhood obesity indicates that fundamental shifts are occurring in both energy intake and expenditure that adversely affect energy balance. The risk of childhood obesity persisting into adulthood is greater in adolescents than in children.24, 45 Many of the metabolic and cardiovascular complications that are commonly associated with adult obesity have their onset in childhood.³ Thus, understanding the early metabolic defects and the antecedents of obesity-related complications in obese children is of great importance.

The authors have previously described studies that have defined the impact of both childhood and adolescent obesity on glucose and lipid metabolism in vivo. Using MR imaging the abdominal visceral and subcutaneous fat depots were quantitated and these different fat depots related to parameters of insulin action and secretion early in the course of obesity. Plasma leptin concentrations and their relationships to specific abdominal fat depots in lean and obese children were described. In addition to the alterations in insulin action and secretion, the authors examined the impact of adolescent obesity on the growth hormone–insulin-like growth factor 1 (IGF₁) axis and binding proteins and their relationship to hyperinsulinemia.