ABSTRACT
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.
Subject(s)
Adipose Tissue , Anthropometry/methods , Body Composition/physiology , Electric Impedance , Skinfold Thickness , Age Factors , Child , Child, Preschool , Chile , Female , Humans , Indicator Dilution Techniques , Male , Overweight , Plethysmography , PubertyABSTRACT
Zinc (Zn) deficiency and obesity can be observed together in some developing countries. Zn deficiency may enhance fat deposition and decrease lean mass accrual, which in turn, appears to influence physical activity (PA), although this has not yet been evaluated in obese children. The objective of the study was to find out the association between measurements of plasma Zn and serum leptin, body composition, and PA in Chilean obese preschool children. Seventy-two 18- to 36-month-old obese children [weight-for-length/height z score (WHZ) > 2.0 SD], belonging to low socioeconomic communities, participated in the study. Plasma Zn, serum leptin, weight, waist circumference, height, total body water (TBW) assessed by deuterium isotopic dilution technique and daily activity, measured by registering 48 h with an accelerometer, were evaluated. We found 82% of children with WHZ > 3 SD. The geometric mean Zn intake was 6.2 +/- 2.5 mg/day. The mean plasma Zn was 91.8 +/- 11.4 microg/dL, with 10% of the children having levels <80 microg/dL. No correlation was found between plasma Zn concentrations and either weight, WHZ, or waist circumference. Serum leptin was lower in males than in females (2.9 +/- 2.8 vs 6.8 +/- 5.0 ng/mL, respectively; p < 0.001). TBW was different between males and females (56.2 +/- 5.4 vs 52.8 +/- 4.3% body weight, respectively; p = 0.004), but no significant association was found between TBW and plasma Zn. Moderate + intense PA, (as percentage of wake time), was greater in males than in females (6.3 +/- 3.1% vs 3.4 +/- 2.3%, respectively; p < 0.001), but it was not significantly correlated to plasma Zn. In conclusion, plasma Zn was not associated with body composition as assessed by TBW, serum leptin, or with the magnitude of physical activity in Chilean overweight preschool children.
