Obesity in children and adolescents

Abstract

Context: Although the prevalence rates of childhood obesity have seemingly been stable over the past few years, far too many children and adolescents are still obese. Childhood obesity, and its associated metabolic complications, is rapidly emerging as one of the greatest global challenges of the 21st century. About 110 million children are now classified as overweight or obese.

Evidence acquisition: In this review we first describe the most recent data on the prevalence, severity, and racial/ethnic differences in childhood obesity. Obesity is associated with significant health problems in the pediatric age group and is an important early risk factor for much of adult morbidity and mortality.

Evidence synthesis: We review the metabolic complications associated with childhood obesity. Particular emphasis is given to the description of studies regarding the impact of varying degrees of obesity on the cardiometabolic risk factors in youth. We further describe studies in obese adolescents that have examined the importance of ectopic lipid deposition in the visceral abdominal depot and in insulin sensitive tissues in relation to the presence of insulin resistance. We end by describing studies that have examined beta-cell function in obese adolescents with normal glucose tolerance.

Conclusions: The growing number of obese children and adolescents worldwide is of great concern. Many obese children and adolescents already manifest some metabolic complications, and these children are at high risk for the development of early morbidity. Understanding the underlying pathogenesis of this peculiar phenotype is of critical importance.

Figure 1

Impact of degree of overweight on cardiometabolic risk factors in children and adolescents. Sys BP, Systolic blood pressure.

Figure 2

Relationship between β-cell function (insulinogenic index; top panel) and insulin sensitivity (WBISI; middle panel) as a function of 2-h glucose category. Data are expressed as least-squares means and 95% confidence intervals (adjusted for age, gender, race/ethnicity, and BMI). For comparisons made between the lowest and more elevated 2-h glucose levels (P < 0.02, P < 0.05 for moderate to high glucose levels). The net response on the insulin feedback system was a decrease in disposition index (bottom panel) at each level of increasing hour glucose category (<0.01 for all comparisons). Modified from Yeckel CW et al. (2005, J Clin Endocrinol Metab 747–754).

Figure 3

Summary hyperbolic feedback curves constructed from all participants grouped by 2-h glucose category. Feedback curves were compared using liner regression in which the logarithm of the IGI was modeled as a function of the logarithm of the WBISI. There was a significant leftward shift (toward IGT) in the insulin feedback curve for increasing 2-h glucose category. This leftward shift remained significant after adjustment for age, gender, race/ethnicity, and BMI. Group comparisons were: less than 100 mg/dl to 100–119 mg/dl (P < 0.001); less than 100 mg/dl to 120–139 mg/dl (P < 0.001); and 100–119 mg/dl to 120–139 mg/dl (P = 0.03). Modified from Yeckel CW et al. (2005, J Clin Endocrinol Metab 747–754).