Anthropometric indicators as predictors of total body fat and cardiometabolic risk factors in Chilean children at 4, 7 and 10 years of age.

BACKGROUND/OBJECTIVE: To compare the association between anthropometric indicators of global and central obesity as predictors of total body fat (TBF) and cardiometabolic risk factors in children. SUBJECTS/METHODS: A total of 1044 children were evaluated at 4 years (n=320), 7 years (n=1044) and 10 years (n=483). The following anthropometric indices were determined: body mass index (BMI) for age (BAZ, WHO), waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR). To estimate TBF we used validated predictive equations. We measured blood sample concentrations of glucose, insulin, triglycerides, total cholesterol, Low-density lipoprotein (LDL) and High-density lipoprotein (HDL), adiponectin, C-reactive protein (CRP) and Insulin-like growth factor-1 (IGF-1). RESULTS: Adiposity and cardiometabolic markers, particularly those related to glucose metabolism increased from 4 years to 10 years. BAZ and WC were highly correlated to body fat at all ages (all r>0.8) but at 10 years WC was more strongly correlated than BAZ (r=0.94 WC vs r=0.88 BAZ, P<0.05); conversely, WHtR was significantly associated with body fat from 7 years (r=0.85) and 10 years (r=0.88). WHR was unrelated all over the period studied at all ages. Anthropometrical adiposity indicators became associated to cardiometabolic markers only from 7 years on with associations being slightly higher at 10 years, particularly for adiponectin and lipid markers. At all ages, BAZ, WC and WHtR performed similarly as cardiometabolic markers (P<0.05) while WHR was a slightly weaker marker. CONCLUSIONS: Relationship between anthropometrical indicators of adiposity and cardiometabolic markers becomes stronger from 7 years onwards; BAZ, WC and WHtR perform similarly as markers of cardiometabolic risk at least until 10 years of age.

Evaluation of simple body composition methods: assessment of validity in prepubertal Chilean children.

BACKGROUND/OBJECTIVE: The aim of this study was to assess the validity of body fatness estimations based on skinfolds and bioelectrical iImpedance analyses (BIA) measurements compared to a three-component model (3C model) in prepubertal Chilean children, considering potential differences by sex and nutritional status. SUBJECTS/METHODS: Four hundred and twenty four Chilean children (198 females and 226 males) were assessed for body composition. Body fat percentage (BF%) was evaluated by Skinfold equations (Slaughter, Ramirez and Huang) and Bioelectrical impedance (BIA: Tanita BC-418MA) using both the equipment and the Ramirez equation. Measurements based on a 3C model constructed from total body water estimates by isotope dilution and from body volume estimates by air displacement plethysmography were used as gold standard. RESULTS: Coefficient of determination (R2) values were higher in overweight and in the whole group of both gender. All slopes were differed significantly from 1, and most intercepts were significantly different from 0. Skinfold Equations: an underestimation of BF% was found for all equations, being higher with the Slaughter equation. BIA: Tanita underestimated BF% in all groups, whereas Ramirez equation shows an overestimation. CONCLUSIONS: Skinfolds and bio-impedance equations serve well to rank children according to their BF%. However, these methods are not accurate for describing body composition in prepubertal Chilean children.