The advantages of a non-restrictive diet for preservation of growth and maturation rates during the treatment of obese children at early stages of their puberty, were investigated comparing two groups of subjects with similar characteristics after one year undergoing two different therapeutic procedures. Both comprised diet, physical training, education and psychological support, and the only difference between them was that energy intake in the control group was restricted to 0.17 MJ/kg of expected body weight for stature, while in the experimental group energetic contents of the diet was fitted to the physiological requirements for age, sex and physical activity (0.25 MJ/kg). It could be found that restriction of energy intake for six months impairs the velocity of growth and maturation and lean tissue accretion. The incidence of desertions was slightly higher in the restricted group, and no relapses were registered in any groups. The applicability of Efficiency Index for the assessment of the results of the treatment was confirmed. The additional advantages of the non-restrictive method is that it is better tolerated and establishes favorable conditions for changing the individual and family style of life, and that it can be applied in the outpatient clinic at the primary level of health care.