ИСТИНА

The epidemic of overweight and obesity that has affected the world's population has become a great concern. Excess fat mass is associated to metabolic syndrome and cardio diseases. The body mass index is widely used to measure adiposity in adults. The WHO has proposed to use the BMI to assess the fat mass in children too. But the proportion of fat mass and fat free mass in children is an important determinant of fitness and health. New indices have been proposed for the analysis of body composition: fat mass index and fat free mass index. The aim of this study was to describe the age and sex specific changes of the FMI and FFMI in Russian schoolchildren and to analyze their relationship with BMI. In a cross-sectional study of physical development of Russian children and adolescents where collected data from 3873 participants aged 7 to 17 years old of both sexes in schools from Moscow, Arkhangelsk and Arkhangelsk region. Body composition was measured by a multyfrequency, tetra-polar bioelectric impedance analyzer Medass. BMI increases throughout 7 to 17 years. It is thought BMI age changes should reflect changes in FM. But we have seen the FM changes do not follow the expected curve of BMI changes. In boys FFMI has a higher growth rate than FMI. In girls FMI has a higher growth rate than FFMI. FMI more accurately describes age-related changes in fat mass and sex differences