Original Paper Received: April 4, 2014 Accepted after revision: October 20, 2014 Published online: December 10, 2014

Ann Nutr Metab 2015;66:26–30 DOI: 10.1159/000369359

Comparison of Methods for the Measurement of Body Composition in Overweight and Obese Brazilian Children and Adolescents before and after a Lifestyle Modification Program Arthur Lyra a Alexandre José Bonfitto a Vera Lucia P. Barbosa a, b Ana Cristina Bezerra a Carlos Alberto Longui a Osmar Monte a Cristiane Kochi a   

 

 

 

 

 

 

a Santa Casa of São Paulo Medical School, Department of Pediatric Endocrinology, São Paulo and b Movere Institute, São Paulo, Brazil  

 

Abstract Aim: To compare the body composition of overweight children and adolescents by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA) before and after physical activity program. Methods: One hundred and eleven patients with mean age (SD) of 12 (1.9) participated in the study. We assessed the weight, height, waist circumference (WC), and body composition by DXA and BIA. Patients underwent a program of diet and physical activity (1 h 30 min/day, 3 times a week for 3 months) and were evaluated before and after this period. Results: Mean initial zBMI were 2.3 (0.5) and waist SDS 5.9 (1.8). Significant differences were observed when we compared the measurements taken by DXA and BIA, respectively: total body fat percentage (40 and 31.5) and fat-free mass (43.1 and 50.6 kg). Regarding the trunk fat by DXA, there was a positive correlation with the WC/height ratio (r = 0.65; p < 0.01). After the intervention period, we observed a reduction in the zBMI, waist SDS, and total body fat and increase of fat-free mass by DXA. BIA only detected reduction in fat. Conclusion: BIA underestimates the percentage of fat and overestimates fat-

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free mass in relation to DXA. There is positive correlation between trunk fat and the ratio WC/height. In addition, DXA detected changes in body composition induced by a short period of physical training, unlike BIA. © 2014 S. Karger AG, Basel

Introduction

The prevalence of overweight and obesity in pediatric population is increasing at an accelerated rate, and childhood obesity is becoming one of the most critical public health concerns. Data from Brazilian Institute of Geography and Statistics (IBGE) show that 18% of male and 15% of female adolescents are overweight and 5.9% and 4%, respectively, are obese [1]. There is a high risk that a child will become an obese adult and an obese adolescent has 80% chance of becoming an obese adult. This group has an increased risk of current comorbidities and subsequent cardiovascular risk [2]. Body mass index (BMI) is the most commonly measured parameter used to classify excess adiposity, although it does not correlate to fat distribution and it cannot differentiate between lean mass and fat [3, 4]. Cristiane Kochi Department of Pediatric Endocrinology Santa Casa of São Paulo Medical School 112 Dr. Cesário Mota Jr. Street – São Paulo, CEP 01238-010 (Brazil) E-Mail ckochi @ uol.com.br

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Key Words Body composition · DXA · BIA · Obesity · Childhood

Patients and Methods One hundred and eleven obese children and adolescents were followed in a Pediatric Endocrinology Center, mean age (SD): 12.0 (1.9) years, participated in this study. Obesity and overweight were defined according to CDC 2000 criteria (>95th percentile and between 85 and 95th percentile, respectively) [10]. Exclusion criteria included hypothyroidism, diabetes mellitus, hypopituitarism, Cushing syndrome, kidney disorders, congenital cardiac disease, and other abnormalities limiting physical activity. Subjects were outpatients beginning a weight-loss program, including physical activity and nutritional recommendation. All patients underwent physical activity at a specialized center, three times a week, for three months. The protocol included physical examination, anthropometric measurements, and body composition evaluation before and after three months. Informed consent approved by the local Institutional Ethics Committee was obtained from all participants before beginning the study.

Body Composition in Overweight Children

The clinical evaluation consisted in detailed history and physical examination, including pubertal classification (Tanner and Marshall). Anthropometric assessments were in agreement with the recommendations of Anthropometric Standardization Reference Manual [11]. Body mass index (BMI) was calculated as body weight (kg) divided by squared height (meters). Waist circumference (WC) was performed with a metric tape, at the mean distance between the last rib and the anterior-superior iliac crest, and it was expressed as a standard deviation score [12] and as a WC/height ratio. Body composition was measured to determine free fat mass (FFM), fat mass (FM), and percentage of body fat (BF%) by use of the two following methods: (i) DXA scanning (Lunar DPX-IQ, version 4.7e, Lunar Radiation Corporation, Madison, WI, USA), according to standardized procedures recommended by the manufacturer; (ii) BIA with a tetrapolar bioanalyzer device (RJL, BIA Quantum). A single trained observer undertook measurements as previously described [11]. Subjects reclined on a flat couch, with limbs not touching each other. Electrodes were placed on the right side of the body between the distal prominences of the radius and ulna; the distal end of the third metacarpal; between the median and lateral malleoli at the ankle; and at the distal end of the third metatarsal. FFM, FM, and BF% were calculated from the measurements of resistance made at 50 kHz using the formula provided by the instrument manufacturer. The evaluation was performed in the morning, with water fasting of eight hours. Physical activity program consisted of training, three times per week, with 90 min each, for three months. The exercises were divided in five phases and the intensity of exercises controlled by Borg reference, in which 5 is considered low and 7 considered moderate intensity, with a heartbeat varying from 120 to 140 rpm. The protocol consisted of elongation, aerobic training and resistance training, motor coordination and rhythm. All patients and their caretakers received nutritional recommendations once a week. Caloric intake was based on the calculation of resting energy expenditure and daily energy needs. The diet planning was made based on the American Heart Association [13]. Statistical analysis was performed using SigmaStat 3.2 (SPSS Inc., Chicago, Ill., USA). Student t test was used to compare the results between the two body composition methods. Depending on the distribution of variables, Paired t test or Wilcoxon was used to compare two measurements in the same patient before and after the program. Spearman Rank Correlation test was used to determine the association between two variables. Statistical significance was defined at p < 0.05.

Results

All patients completed the program. The results of anthropometric measurements before and after the physical activity program are shown in table 1. Regarding body composition, when the data obtained by DXA were compared to those obtained by BIA, there was a significant decrease in total percentage FM (40.0 Ann Nutr Metab 2015;66:26–30 DOI: 10.1159/000369359

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In 2006, Wells et al. suggested that anthropometric measurements should be combined with BMI to evaluate body composition in order to avoid misdiagnosis of weight excess [4]. Obesity currently remains defined by anthropometric criteria (BMI), but it has poor sensitivity for monitoring response to treatment; so body composition measurement could improve management (Wells, 2014) [5]. Some of the noninvasive methods for the evaluation of body composition include skinfold thickness, bioelectrical impedance analysis (BIA), and dual-energy X-ray absorptiometry (DXA). Measurement of fat mass (FM) and free fat mass (FFM) by DXA is appropriate to study body composition in both children and adults [6, 7]. It’s a safe method with minimum radiation (

Comparison of methods for the measurement of body composition in overweight and obese Brazilian children and adolescents before and after a lifestyle modification program.

To compare the body composition of overweight children and adolescents by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry ...
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