Resting metabolic rate in obese children before, during and after weight loss.

Resting metabolic rate (RMR) and body composition were measured by indirect calorimetry and body impedance analysis in 14 obese children before weight loss, during weight reduction for 3 weeks with a conventional hypocaloric diet (730 kcal/3050 kJ) and 12 months after weight loss. The initial weight reduction (5.8 +/- 1.2 kg) resulted in a decrease in RMR and fat free mass (FFM) of 17 +/- 10 per cent (P less than 0.001) and 3.1 +/- 2.3 kg (P less than 0.001), respectively. Prior to weight loss (r2 = 0.89, P less than 0.001) and after 12 months follow up (r2 = 0.88, P less than 0.001) RMR correlated positively with FFM. Changes in RMR after 3 weeks weight loss and throughout the follow-up were positively correlated with changes in FFM (r2 = 0.29, P less than 0.05 and r2 = 0.90, P less than 0.001). Our data indicate that RMR in obese children considerably decreased during a 3 weeks weight reduction, but no sustained depression of the metabolic rate after 12 months was found.