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Body composition reference percentiles of healthy Iranian children and adolescents in southern Iran.

BACKGROUND
The prevalence of childhood obesity has risen greatly worldwide. However, assessment of obesity among children and adolescents is further complicated by the changes occurring in the body composition during the growth. The aim of this study is to create gender-specific percentile curves for total body fat percentage (TBFP), total body fat mass (TBFM), fat mass index (FMI), and fat free mass index (FFMI) in healthy Iranian children and adolescents.


METHODS
In this cross-sectional study, 472 healthy Iranian children and adolescents (234 girls and 238 boys) aged 9-18 years old participated. TBFP and TBFM were measured by Dual-Energy X-ray Absorptiometry (DEXA). Weight, height, and waist circumference (WC), pubertal stage and level of physical activity were also recorded.


RESULTS
Mean TBFM, TBFP and FMI in girls were significantly more than boys (P < 0.001). The median TBFM in boys increased from 4.8 Kg to 7.5 Kg and in girls from 6.0 Kg to 15.6 Kg. The percentile curves of TBFP in boys were down sloping compared with that in girls (19% increase in girls and 21% decrease in boys from 9-18 years of age). We showed TBFP and FMI had a more complicated relationship with BMI depending on gender and level of BMI, but FFMI consistently increased with BMI in both genders. Also, we found that waist circumference -as a marker of metabolic syndrome-had the greatest correlation with FMI (P < 0.001) between DEXA measured parameters.


CONCSLUSION
This study presents normative data for body composition in healthy Iranian children and adolescents and would be useful in adiposity assessment. Our study showed that Iranian children and adolescents had lower total body fat in all age groups and percentiles in comparison with those reported from western children.