The article presents our experience of low-carbohydrate ketogenic diet usage in fifteen children with primary stage 1-3 constitutional obesity. Criteria for assessment were dynamic changes of weight, serum lipid profile, changes in percentage of body fat content according to "total body" densitometry data, changes in indices of insulin resistance. The obtained data support that this type of diet is well tolerated by children; it normalizes cholesterol, triglyceride, and beta-lipoprotein serum values; reduces indices of insulin resistance while effective weight and appetite loss.