Reference centiles for evaluating total body fat development and fat distribution by dual-energy x-ray absorptiometry among children and adolescents aged 3-18 years

Background & aims: The rise in the prevalence of childhood obesity has increased the demand for accurately evaluating body fatness in pediatric population. The aim of this study was to provide a series of sex- and age-specific body fat reference centiles for evaluating total body fat development and fat distribution in Chinese children and adolescents using dual-energy x-ray absorptiometry (DXA).

Methods: A nationwide sample of Chinese children and adolescents aged 3-18 years (n = 12,790) was drawn from a cross-sectional survey of the China Child and Adolescent Cardiovascular Health study (2013-2019). Fat measurements, including total fat mass index (FMI), total body fat percentage (BF%), regional FMI, trunk to leg (T/L) fat ratio and android to gynoid (A/G) fat ratio, were derived from whole body DXA scans. Sex- and age-specific centiles were estimated using the lambda-mu-sigma method and then compared with values derived from the US National Health and Nutrition Examination Survey (1999-2004) and Korean National Health and Nutrition Examination Survey (2008-2011).

Results: During early childhood, almost all body fat parameters decreased with age, except an increase in A/G ratio. After 7 years onward, drastic upward trends of total FMI and BF% were exhibited in boys till 10 years, followed by opposite downward trends during 11-14 years; while sustained increase of FMI was shown in girls across ages accompanied by relatively constant BF% levels. Meanwhile, steady increases were noticed for A/G ratio and T/L ratio, which were more pronounced in boys. In addition, the proposed body fat references were much lower than the US but similar to Koreans despite of subtle differences.

Conclusions: This is the first study to present a set of DXA-based body fat reference for Chinese children and adolescents aged 3-18 years. The new reference provides clinicians and researchers a useful tool for assessing body fat development and distribution patterns throughout early childhood and adolescence.