High Prevalence of Obesity but Low Physical Activity in Children Aged 9–11 Years in Beijing

Figures & data

Table 1 Characteristics of the Participants by Weight Status

Characteristics	Total (n=10,855)	Weight Status			P-value*
		Normal Weight (n=6381)	Overweight (n=1910)	Obesity (n=2564)	P ^a	P ^b	P ^c
Age (years)					<0.01	<0.01	<0.01
6–8	4179 (38.5%)	2721 (42.6%)	580 (30.4%)	878 (34.2%)
9–11	3382 (31.2%)	1775 (27.8%)	670 (35.1%)	937 (36.5%)
12–14	2341 (21.6%)	1270 (19.9%)	478 (25.0%)	593 (23.1%)
15–18	953 (8.8%)	615 (9.6%)	182 (9.5%)	156 (6.1%)
Sex					<0.01	<0.01	<0.01
Boy	5500 (50.7%)	2933 (46.0%)	969 (50.7%)	1598 (62.3%)
Girl	5355 (49.3%)	3448 (54.0%)	941 (49.3%)	966 (37.7%)
Father obesity					<0.01	<0.01	<0.01
Yes	2474 (22.8%)	1123 (17.6%)	474 (24.8%)	877 (34.2%)
No	8381 (77.2%)	5258 (82.4%)	1436 (75.2%)	1687 (65.8%)
Father’s education					<0.01	<0.01	0.39
Primary school	79 (0.7%)	52 (0.8%)	11 (0.6%)	16 (0.6%)
High School	4505 (41.5%)	2538(39.8%)	853 (44.7%)	1114 (43.4%)
University Degree	5766 (53.1%)	3469 (54.4%)	961 (50.3%)	1336 (52.1%)
Graduated Degree	505 (4.7%)	322 (5.0%)	85 (4.5%)	98 (3.8%)
Mother obesity					<0.01	<0.01	<0.01
Yes	917 (8.4%)	350 (5.5%)	195 (10.2%)	372 (14.5%)
No	9938 (91.6%)	6031 (94.5%)	1715 (89.8%)	2192 (85.5%)
Mother’s education					<0.01	<0.01	0.43
Primary school	111 (1.0%)	63 (1.0%)	20 (1.0%)	28 (1.1%)
High School	4220 (38.9%)	2395 (37.6%)	806 (42.2%)	1019 (39.8%)
University Degree	6191 (57.0%)	3690 (57.8%)	1043 (54.6%)	1458 (56.9%)
Graduate Degree	333 (3.1%)	233 (3.7%)	41 (2.1%)	59 (2.3%)
Mother’s glucose level during pregnancy					0.21	<0.01	<0.01
High	852 (7.8%)	476 (7.5%)	125 (6.5%)	251 (9.8%)
Normal	10,003 (92.2%)	5905 (92.5%)	1785 (93.5%)	2313 (90.2%)
Infant breast feeding					0.47	<0.05	0.33
Yes	7969 (73.4%)	4727 (74.1%)	1399 (73.2%)	1843 (71.9%)
No	2886 (26.6%)	1654 (25.9%)	511 (26.8%)	721 (28.1%)
Birth weight ≥4 kg					<0.01	<0.01	<0.01
Yes	1490 (13.7%)	763 (12.0%)	275 (14.4%)	452 (17.6%)
No	9365 (86.3%)	5618 (88.0%)	1635 (85.6%)	2112 (82.4%)
Household income (ten thousand yuan/year)					0.07	<0.01	<0.05
<10	3861 (35.6%)	2212 (34.7%)	722 (37.8%)	927 (36.2%)
10–20	4225 (38.9%)	2463 (38.6%)	713 (37.3%)	1049 (40.9%)
20–30	1747 (16.1%)	1072 (16.8%)	291 (15.2%)	384 (15.0%)
>30	1022 (9.4%)	634 (9.9%)	184 (9.6%)	204 (8.0%)
Siblings					1	<0.01	<0.01
Yes	3545 (32.7%)	2167 (34.0%)	649 (34.0%)	729 (28.4%)
No	7310 (67.3%)	4214 (66.0%)	1261 (66.0%)	1835 (71.6%)
Frequency of breakfast					<0.01	<0.01	0.88
<4 times/week	936 (8.6%)	494 (7.7%)	187 (9.8%)	255 (9.9%)
≥4 times/week	9919 (91.4%)	5887 (92.3%)	1723 (90.2%)	2309 (90.1%)
Having breakfast at home					<0.05	0.61	0.15
Yes	8396 (77.3%)	4969 (77.9%)	1443 (75.5%)	1984 (77.4%)
No	2459 (22.7%)	1412 (22.1%)	467 (24.5%)	580 (22.6%)
Having dinner with parents					0.33	0.93	0.49
Yes	7774 (71.6%)	4584 (71.8%)	1351 (70.7%)	1839 (71.7%)
No	3081 (28.4%)	1797 (28.2%)	559 (29.3%)	725 (28.3%)
Frequency of restaurant					0.91	0.67	0.65
<3 times/month	5229 (48.2%)	3080 (48.3%)	925 (48.4%)	1224 (47.7%)
≥3 times/month	5626 (51.8%)	3301 (51.7%)	985 (51.6%)	1340 (52.3%)
Watching TV					0.17	<0.05	0.53
<2 hours/day	9628 (88.7%)	5701 (89.3%)	1684 (88.2%)	2243 (87.5%)
≥2 hours/day	1227 (11.3%)	680 (10.7%)	226 (11.8%)	321 (12.5%)
Frequency of exercise					0.13	<0.01	<0.01
Never	1173 (10.8%)	588 (9.2%)	198 (10.4%)	387 (15.1%)
1–3 times/week	5273 (48.6%)	3036 (47.6%)	925 (48.4%)	1312 (51.2%)
4–6 times/week	2165 (19.9%)	1312 (20.6%)	398 (20.8%)	455 (17.7%)
Everyday	2244 (20.7%)	1445 (22.6%)	389 (20.4%)	410 (16.0%)
Exercise time					<0.01	<0.01	<0.01
<90 minutes/week	3409 (31.4%)	1828 (28.6%)	630 (33.0%)	951 (37.1%)
90–120 minutes/week	2875 (26.5%)	1705 (26.7%)	511 (26.8%)	659 (25.7%)
120–150 minutes/week	1731 (15.9%)	1059 (16.6%)	276 (14.5%)	396 (15.4%)
≥150 minutes/week	2840 (26.2%)	1789 (28.0%)	493 (25.8%)	558 (21.8%)
Sleep duration					<0.01	<0.01	0.49
<9 hours/day	7741 (71.3%)	4455 (69.8%)	1413 (74.0%)	1873 (73.0%)
≥9 hours/day	3114 (28.7%)	1926 (30.2%)	497 (26.0%)	691 (27.0%)

Notes: *Results from the chi-square test. P ^a referred to the comparison between normal weight and overweight. P ^b referred to the comparison between normal weight and obesity. P ^c referred to the comparison between overweight and obesity. Statistically significant (P < 0.05) were marked in bold.

Figure 1 The percentage of overweight and obesity (by age group) for boys and girls. ^a P<0.05 compared with boys; ^b P<0.05 compared with children aged 6–8 years; ^c P<0.05 compared with children aged 9–11 years; ^d P<0.05 compared with children aged 12–14 years; ^e P<0.05 compared with children aged 15–18 years.

Figure 2 Logistic regression analysis of risk factors for overweight/obesity. Multivariate odds ratios (OR) and 95% confidence interval (CI) from bivariate regression models were used in the analysis. Variables including age, sex, father obesity, father’s education, mother obesity, mother’s education, mother’s glucose level during pregnancy, infant breastfeeding, birth weight ≥4 kg, household income (ten thousand yuan/year), siblings, frequency of breakfast, having breakfast at home, having dinner with parents, frequency of restaurant, watching TV, frequency of exercise, exercise time and sleep duration were entered in the model.

Figure 3 Distribution and percentages of exercise time by weight groups in children aged 9–11 years. * means P<0.05.

Figure 4 Distribution and percentages of exercise time by age and weight groups.

Table 2 Unconditional Logistic Regression Analysis of Exercise Time According to the Age Group

Exercise Time (Minutes/Week)	Age Group
	6–8 Years OR (95% CI)	9–11 Years OR (95% CI)	12–14 Years OR (95% CI)	15–18 Years OR (95% CI)
<120/≥120	2449/1730	2229/1153	1193/1148	413/540
Univariate	1.00 (reference)	0.732 (0.667–0.804)	1.362 (1.230–1.508)	1.851 (1.606–2.134)
P		<0.01	<0.01	<0.01
Model 1	1.00 (reference)	0.753 (0.685–0.828)	1.411 (1.274–1.564)	1.884 (1.633–2.173)
P		<0.01	<0.01	<0.01
Model 2	1.00 (reference)	0.827 (0.751–0.911)	1.829 (1.633 −2.050)	2.350 (2.020–2.734)
P		<0.01	<0.01	<0.01
Model 3	1.00 (reference)	0.855 (0.775–0.943)	1.913 (1.687 −2.170)	2.218 (1.852–2.656)
P		<0.01	<0.01	<0.01

Notes: Multivariate odds ratios (OR) and 95% confidence intervals (CI) from unconditional logistic regression models were used in the analysis. Model 1: adjusted for gender and body weight (normal, overweight, obesity). Model 2: adjusted for Model 1+ father obesity, father’s education, mother obesity, mother’s education, mother’s glucose level during pregnancy, infant breast feeding, birth weight ≥4 kg, household income (ten thousand yuan/year) and siblings. Model 3: adjusted for Model 2+ frequency of breakfast, having breakfast at home, having dinner with parents, frequency of restaurant, watching TV and sleep duration.