Table 2 Body composition parameters of subjects stratified by sex and pubertal status

Age, years

8.5 ± 2.1

8.1 ± 1.5

0.483

13.0 ± 1.7

11.3 ± 2.8

0.007

< 0.001

< 0.001

Body mass index, z-score

-0.63 ± 1.23

-0.14 ± 1.26

0.145

0.14 ± 1.19

0.47 ± 0.89

0.247

0.019

0.045

Fat percentage

19.9 ± 5.6

23.3 ± 4.9

0.020

22.0 ± 8.6

27.3 ± 6.8

0.011

0.301

0.015

Truncal fat percentage

15.7 ± 5.9

17.5 ± 5.3

0.232

17.9 ± 8.7

21.5 ± 7.3

0.094

0.270

0.023

Fat free mass, kg

19.4 ± 5.9

19.9 ± 4.8

0.695

36.9 ± 11.1

32.6 ± 10.4

0.129

< 0.001

< 0.001

Appendicular skeletal muscle mass, kg

6.41 ± 3.09

7.04 ± 2.13

0.382

15.08 ± 5.57

12.53 ± 4.78

0.066

< 0.001

< 0.001

Total body water, percentage

58.6 ± 4.1

56.1 ± 3.6

0.018

57.2 ± 6.3

53.2 ± 5.0

0.011

< 0.001

< 0.001

Muscle-to-fat ratio

1.34 ± 0.41

1.19 ± 0.26

0.099

1.59 ± 0.53

1.05 ± 0.24

< 0.001

0.050

0.045

Sarcopenic index, kg/m²

3.97 ± 1.10

4.33 ± 0.71

0.149

6.20 ± 1.42

5.39 ± 1.13

0.021

< 0.001

< 0.001

Basal metabolic rate, kcal

1114.0 ± 135.6

1019.2 ± 104.5

0.005

1494.9 ± 254.5

1287.0 ± 254.5

0.003

< 0.001

< 0.001

Data are presented as mean ± standard deviation. Appendicular skeletal muscle mass (ASMM) = the sum of muscle mass of four limbs, muscle-to-fat ratio [MFR = ASMM (kg) /fat mass (kg)] and sarcopenic index [(SI = ASMM (kg) / height (meter)²]. P¹ compares between prepubertal boys and girls; p² compares between adolescent boys and girls; p³ compares between prepubertal and adolescent boys and p⁴ compares between prepubertal and adolescent girls. Bold values denote statistical significance at the p ≤ 0.05 level