Table 4.

Fat-free Mass/Height² (kg/m²) by Annual Age from 8 to 18 Years and Decades of Birth.

Age	Birth Decade (BD)
(years)	1960≤BD<1970			1970≤BD<1980			1980≤BD<1990			1990≤BD<2000
Boys	n	mean	std	n	mean	std	n	mean	std	n	mean	std
8≤age<9	6	14.09	1.05	6	14.53	2.00	35	13.46	1.33	35	14.01	1.58
9≤age<10	10	14.76	1.33	21	13.64	1.08	41	13.92	1.71	28	14.18	1.95
10≤age<11	9	14.93	0.88	32	13.67	1.40	34	14.28	1.36	35	14.18	1.87
11≤age<12	20	14.37	0.76	41	13.99	1.33	45	14.23	1.58	32	14.36	1.68
12≤age<13	28	15.28	1.40	39	14.66	1.82	37	15.03	1.74	37	15.04	1.94
13≤age<14	24	15.59	1.94	42	15.20	2.04	34	15.49	1.97	28	15.65	1.98
14≤age<15	25	16.69*	1.91	37	16.36	2.03	47	16.72	2.26	28	16.35	2.47
15≤age<16	27	17.90*	2.07	44	17.56	2.18	38	17.28*	2.41	23	16.62	1.85
16≤age<17	38	19.01*	2.10	40	17.76	2.51	36	18.41*	2.37	19	17.61	2.24
17≤age<18	26	18.95*	1.62	43	18.49	2.21	43	18.72*	2.11	14	17.71	2.29
Girls
8≤age<9	5	12.59	1.48	8	11.97	1.97	38	13.63	1.50	30	13.21	1.54
9≤age<10	4	13.72	1.27	20	13.44	1.50	38	13.36	1.74	25	13.31	1.22
10≤age<11	6	14.36	1.00	30	13.69	1.46	49	13.62	1.85	21	13.67	1.38
11≤age<12	15	14.02	1.42	33	13.84	1.56	48	14.13	2.16	15	13.76	1.61
12≤age<13	19	14.72	1.50	34	14.40	1.71	47	14.57	1.86	17	14.16	1.66
13≤age<14	26	15.13	1.49	34	15.14	1.75	41	15.49	2.18	17	15.18	1.26
14≤age<15	30	15.86	1.22	32	15.48	1.69	41	16.07	1.96	15	15.52	1.23
15≤age<16	22	16.25	1.67	42	16.04	1.46	28	16.29	1.92	17	15.71	1.74
16≤age<17	27	16.34	1.41	39	15.89	1.5	40	15.95	2.07	10	15.43	2
17≤age<18	30	16.11	1.51	36	16.12	1.64	47	16.39	2.11	10	16.04	2.08

^*Mean BMI significantly less than mean BMI for 1990–2000 (p-value < 0.05).