INTRODUCTION: Over the past several decades, the problem of pediatric exogenous constitutional obesity has acquired the status of a non-infectious pandemic of the 21st century. Statistics shows that both the prevalence of overweight and obese children and the incidence of morbid obesity, its complications and metabolic syndrome are increasing, which most is alarming for healthcare workers. This tendency requires specialists to understand the metabolic bases of formation of obesity, to search for new ways to treat and prevent the disease, as well as to prevent the development of complications. CONCLUSION: The given review considers the main features of metabolic alterations in the formation of childhood obesity, which can be an additional risk factor for both the development of the disease itself, and of its complications, the main ones being physiological insulin resistance of adolescents and a significant secretion of insulin-like growth factor-1 in children in the period of active growth. Understanding of metabolic features of the development of obesity at the pathophysiological and biochemical levels can become the basis for development of the ways to influence these processes. Of attention is the fact of a high prevalence of obesity complications and metabolic syndrome in childhood, with a continuing tendency to growth proportional to increase in the prevalence of obesity itself. A key point is the current absence of ways to predict obesity complications in children. Taking into account very limited possibilities of treatment of childhood obesity and its complications, the existence of prognostic markers may contribute to prevention or earlier, timely diagnosis of the main obesity complications, with a further decline of disability and mortality at a young age, as well as a considerable improvement of the quality of life of obese patients. The presented data require an in-depth analysis of mechanisms of development of childhood obesity — one of the most common problems in the world, and permit to reconceive the problems of treatment and prevention, to open up new prospects for creation of new approaches to diagnosis and control of this disease and its complications.