70 CHANGES OF BODY COMPOSITION IN OBESE CHILDREN DURING WEIGHT REDUCTION (WR) AS MEASURED BY DEUTERIUM DILUTION

AIMS: 1) To investigate whether physical activity during WR in obese children reduces loss of lean body mass. 2) To establish a group-specific relation between body water (TBW) and bioelectrical impedance (BIA).METHODS: 67 obese, but healthy children: 23 boys, 44 girls: 13.9 ± 1.8 y, 166.0 ± 10.1 cm, 84.3 ± 17.2 kg, 40-d supervised WR program (1000 kcal/d diet combined with a 2-h sport program every day). After overnight fast, measurement of: 1) body weight (BW), 2) skinfold thickness, sum of 4 sites (SST) using a Houltain caliper, 3) BIA using an AKERN 101, 4) TBW (oral load of 0.4 ml 99.8% D2O/kg BW, pre-dose urine and 3-h post-dose serum sample, analysis of 2H enrichment as described [1, 2], CV < 1%.)RESULTS: see table; linear regression revealed significant correlation (before WR: r = 0.906, after: r = 0.913) between TBW and BIA.DISCUSSION: 1) TBW is constant during WR, weight loss is merely due to a loss of fat mass. 2) A relation between BIA and TBW was found which was stable during WR.