The present study aimed at comparing fat and lean masses between children and
adolescents with and without Down syndrome (DS) and evaluating the presence of sexual
dimorphism. Total and regional fat and lean masses were assessed by dual energy X-ray
absorptiometry (DXA) and the percentage of body fat (%BF) by air-displacement
plethysmography (ADP) in 31 participants with DS and 32 controls. Waist circumference
(WC) was also measured. Analysis of covariance and the Student’s t-test were used to
compare variables between groups and between sexes within the same group. There were
no significant differences in %BF, WC or body mass index (BMI) between groups. Females
with DS showed higher fat and lean masses in the trunk, and lower fat and lean masses in
the lower limbs compared with females without DS (all p 0.05). Males with DS showed
higher fat masses in the whole body and upper limbs, and lower lean masses in the whole
body and lower limbs compared with males without DS (all p 0.05). Females in both
groups showed higher levels of fat, and lower levels of lean than did their respective males
(all p 0.05). Youths with DS showed higher fat and lower lean than their non-DS peers.
The increased truncal fat in females with DS might indicate a higher risk of metabolic
syndrome in this group. Sexual dimorphism in youths with and without DS was very
similar. BMI, WC and %BF were not effective indicators of increased risk in youths with DS.