Body composition and insulin resistance in children

Metabolism and immunity are inextricably linked both to each other and to organism-wide function, allowing mammals to adapt to changes in their internal and external environments. In the modern context of obesogenic diets and lifestyles, however, these adaptive responses can have deleterious consequences. In this Review, we discuss the pleiotropic actions of inflammation and insulin resistance in metabolic homeostasis and disease. An appreciation of the adaptive context in which these responses arose is useful for understanding their pathogenic actions in disease.

To test the hypothesis that in a healthy pediatric population body mass index (BMI) (kilograms per meter square) is a valid measure of fatness that is independent of age for both sexes. Total body fat (TBF) (in kilograms) and percent of body weight as fat (PBF) were estimated by dual energy x-ray absorptiometry (DXA) in 198 healthy Italian children and adolescents between 5 and 19 years of age. We developed multiple regression analysis models with TBF and percent body fat as dependent variables and BMI, age, and interaction terms as independent variables. Separate analyses were conducted for boys and girls. BMI was strongly associated with TBF (R2 = 0.85 and 0.89 for boys and girls, respectively) and PBF (R2 =0.63 and 0.69 for boys and girls, respectively). Confidence limits on BMI-fatness association were wide, with individuals of similar BMI showing large differences in TBF and in PBF. Age was a significant covariate in all regression models. Addition of nonlinear terms for BMI did not substantially increase the R2 for TBF and PBF models in boys and girls. Our results support the use of BMI as a fatness measure in groups of children and adolescents, although interpretation should be cautious when comparing BMI across groups that differ in age or when predicting a specific individual's TBF or PBF.

To determine whether using a combination of body mass index (BMI) and waist circumference (WC) or waist-to-height ratio (W/Hr) is clinically helpful in identifying children with high metabolic and cardiovascular risks. Caucasian children (M/F: 740/739; n = 1479; ages 5 to 15 years) were studied. Anthropometry, blood pressure, and venous fasting blood samples tested for triacylglycerol, HDL cholesterol, and glucose were measured. Overweight children with a large waist (>90(th) percentile) or high W/Hr (>0.5) but not obese or normal-weight children had significantly greater chances of being at high metabolic and cardiovascular risk than normal-weight children (OR: 7; 95% CI: 3.63-13.48; P < .001, OR: 8.16; 95% CI: 3.87-17.23; P < .001, respectively) with a low waist measurement (