Characteristics of students from Zhejiang
| Characteristics | Total (n=23 543) | Boys | Girls | P values |
| (n=12 068, 51.3%) | (n=11 475, 49.7%) | |||
| Age (years) | 0.577 | |||
| ≤13 | 5159 (21.9) | 2689 (22.3) | 2470 (21.5) | |
| 14 | 4300 (18.3) | 2192 (18.1) | 2108 (18.4) | |
| 15 | 3730 (15.8) | 1905 (15.8) | 1825 (15.9) | |
| ≥16 | 10 354 (44.0) | 5282 (43.8) | 5072 (44.2) | |
| Area | 0.031 | |||
| Urban | 9022 (38.3) | 4544 (37.7) | 4478 (39.0) | |
| Rural | 14 521 (61.7) | 7524 (62.3) | 6997 (61.0) | |
| Types of school | 0.008 | |||
| Middle school | 12 207 (51.8) | 6364 (52.7) | 5843 (50.9) | |
| Academic high school | 6477 (27.5) | 3223 (26.7) | 3254 (28.4) | |
| Vocational high school | 4859 (20.6) | 2481 (20.6) | 2378 (20.7) | |
| Paternal education | 0.0136 | |||
| Middle or below | 13 568 (57.6) | 6908 (57.2) | 6660 (58.0) | |
| High school | 5100 (21.7) | 2628 (21.8) | 2472 (21.5) | |
| College or above | 3129 (13.3) | 1575 (13.1) | 1554 (13.5) | |
| Unknown | 1746 (7.4) | 957 (7.9) | 789 (7.0) | |
| Maternal education | <0.0001 | |||
| Middle or below | 14 530 (61.7) | 7292 (60.4) | 7238 (63.1) | |
| High school | 4363 (18.5) | 2271 (18.8) | 2092 (18.2) | |
| College or above | 2736 (11.6) | 1392 (11.5) | 1344 (11.7) | |
| Unknown | 1914 (8.1) | 1113 (9.2) | 801 (7.0) | |
| Parental marital status | 0.0004 | |||
| Married | 21 151 (89.8) | 10 924 (90.5) | 10 227 (89.1) | |
| Other | 2392 (10.2) | 1144 (9.5) | 1 248 (10.9) | |
| Academic performance | <0.0001 | |||
| Excellent | 5448 (23.1) | 2731 (22.6) | 2717 (23.7) | |
| Middle | 11 765 (50.0) | 5727 (47.5) | 6038 (52.6) | |
| Poor | 6330 (26.9) | 3610 (29.9) | 2720 (23.7) | |
| Self-reported health | <0.0001 | |||
| Very good/good | 12 415 (52.7) | 6758 (56.0) | 5657 (49.3) | |
| Fair | 9563 (40.6) | 4495 (37.2) | 5068 (44.2) | |
| Very bad/bad | 1293 (5.5) | 650 (5.4) | 643 (5.6) | |
| Unknown | 272 (1.2) | 165 (1.4) | 107 (0.9) | |
| Loneliness | <0.0001 | |||
| Never/occasionally | 15 122 (64.2) | 8082 (67.0) | 7040 (61.3) | |
| Sometimes | 5783 (24.6) | 2698 (22.4) | 3085 (26.9) | |
| Often/always | 2638 (11.2) | 1288 (10.6) | 1350 (11.8) | |
| Physical activity (day/week) | <0.0001 | |||
| 0 | 4883 (20.7) | 2079 (17.2) | 2804 (24.5) | |
| 1–2 | 5690 (24.2) | 2703 (22.4) | 2987 (26.0) | |
| 3–5 | 8050 (34.2) | 4237 (35.1) | 3813 (33.2) | |
| 6–7 | 4920 (20.9) | 3049 (25.3) | 1871 (16.3) | |
| Breakfast (day/week) | <0.0001 | |||
| 0 | 473 (2.0) | 289 (2.39) | 184 (1.60) | |
| 1–2 | 599 (2.5) | 298 (2.47) | 301 (2.62) | |
| 3–4 | 1249 (5.3) | 667 (5.53) | 582 (5.07) | |
| ≥5 | 21 222 (90.2) | 10 814 (89.6) | 10 408 (90.7) | |
| Fruit (times/day) | 0.01 | |||
| ≥3 | 6847 (29.1) | 3453 (28.6) | 3394 (29.6) | |
| 1–2 | 9945 (42.2) | 5213 (43.2) | 4732 (41.2) | |
| <1 | 6751 (28.7) | 3402 (28.2) | 3349 (29.2) | |
| Vegetable (times/day) | 0.40 | |||
| ≥3 | 11 775 (50.0) | 5984 (49.6) | 5791 (50.5) | |
| 1–2 | 9884 (42.0) | 5108 (42.3) | 4776 (41.6) | |
| <1 | 1884 (8.0) | 976 (8.1) | 908 (7.9) | |
| Carbonated beverages | 0.19 | |||
| None | 9133 (38.8) | 4717 (39.1) | 4416 (38.5) | |
| 1–6 times/week | 12 792 (54.3) | 6529 (54.1) | 6263 (54.6) | |
| 1–2 times/day | 1146 (4.9) | 600 (5.0) | 546 (4.7) | |
| ≥3 times/day | 472 (2.0) | 222 (1.8) | 250 (2.2) | |