Childhood obesity has become a serious public health problem. Nutritional therapy plays an important role in its prevention and treatment. A nonrandomized clinical trial was conducted in 40 obese children and adolescents who underwent a complete medical history and assessment of eating habits through 24-hour food recall and a frequency of food consumption questionnaire. In all patients, body weight, height, skinfold thickness, waist and hip circumferences and fasting glucose, total cholesterol, high density lipoprotein (HDL)-cholesterol, low density lipoprotein (LDL)-cholesterol, and triglyceride levels were measured. The nutritional intervention consisted of identifying the calorie consumption and nutrient intake, and participants were given advice aimed at changing eating habits with a healthy normocaloric diet. After 4 months, biochemical, anthropometric and dietary indicators were measured again. Significant reductions were observed in body weight (56.0 +/- 16.5 to 54.4 +/- 16.1 kg), body mass index (26.5 +/- 3.7 to 25.1 +/- 3.1), waist circumference (86.4 +/- 11.6 to 81.4 +/- 11.4 cm) and mid-arm circumference (29.0 +/- 5.0 to 26.0 +/- 4.2 mm). Significant reductions were also observed in total cholesterol (167.1 +/- 30.0 to 156.0 +/- 26.5 mg/dl) and LDL-cholesterol (103.0 +/- 21.4 to 84.6 +/- 26.0 mg/dl). A significant increase was found in HDL values (38.0 +/- 7.8 to 43.4 +/- 9.3 mg/dl). In all comparisons, the p-value was < 0.05. Counseling aimed at changing eating habits is effective in reducing body weight and improves lipid profile in children and adolescents with obesity. Copyright 2009 Sociedad Española de Endocrinología y Nutrición. Published by Elsevier Espana. All rights reserved.