Table 1.

Demographic characteristics of participant

Variables	Boys	% of Sub-Group	Girls	% of Sub-Group	All	% of Sub-Group
	N		N		N
Age (years)
36–12	4724	61.5	4712	62.2	9436	61.8
13–17	2961	38.5	2864	37.8	5825	38.2
Region
Urban	1992	25.9	1995	26.3	3987	26.1
Suburban	2093	27.2	2071	27.3	4164	27.3
Rural	2566	33.4	2487	32.8	5053	33.1
Poor rural	1034	13.5	1023	13.5	2057	13.5
Family income
Low	4628	60.2	4528	59.8	9156	60.0
Medium	1195	15.5	1153	15.2	2348	15.4
High	360	4.7	312	4.1	672	4.4
Unknown	1502	19.5	1583	20.9	3085	20.2
Leisure exercise
No	4294	55.9	4537	59.9	8831	57.9
Yes	3391	44.1	3039	40.1	6430	42.1
Leisure SB
≦2 h/d	2952	38.4	2928	38.6	5880	38.5
> 2 h/d	4733	61.6	4648	61.4	9381	61.5
BMI status
Obesity	991	12.9	631	8.3	1622	10.6
Overweight	1140	14.8	875	11.5	2015	13.2
Normal	5024	65.4	5668	74.8	10,692	70.1
Underweight	530	6.9	402	5.3	932	6.1