The aim of this research was to assess the influence of dietary intervention on weight loss and resting energy expenditure (REE) in 20 obese and overweight adolescents (BMI = 29 +/- 3,8 kg/m2) aged 15-18 years. Nutritional habits and nutritional status were estimated before and after the introduction of low-calorie diet. Measurements of REE were carried out by indirect calorimetry in a respiratory chamber Nutritional intervention had a significant influence in decreasing body weight (from 85 +/- 14.3 kg to 82.5 +/- 12.8 kg), BMI and fat mass. Muscle mass was found to be significantly elevated (p < 0.050). REE did not decline significantly due to nutritional intervention (p > 0.05; p = 0.84).