Table 1 The characteristics of study population by survey year (CHNS 2004–2011)
Survey year | 2004 | 2006 | 2009 | 2011 | F/χ² | P |
|---|---|---|---|---|---|---|
Social demographics | ||||||
Age (years) | ||||||
Mean ± SD | 32.8 ± 7.3 | 34.3 ± 7.6 | 34.6 ± 7.4 | 35.6 ± 7.0 | 145.46 | < 0.001 |
 15–34 | 880 (50.7%) | 846 (43.8%) | 677 (40.2%) | 469 (36.1%) | 73.41 | < 0.001 |
 35–44 | 855 (49.3%) | 1087 (56.2%) | 1008 (59.8%) | 831 (63.9%) |  |  |
Residence location | ||||||
 Urban | 587 (33.8%) | 659 (34.1%) | 558 (33.1%) | 433 (33.3%) | 0.48 | 0.924 |
 Rural | 1148 (66.2%) | 1274 (65.9%) | 1127 (66.9%) | 867 (66.7%) |  |  |
Education level | ||||||
 Non/primary school | 508 (29.5%) | 505 (26.4%) | 465 (28.2%) | 346 (26.9%) | 81.10 | < 0.001 |
 Junior school | 778 (45.2%) | 856 (44.7%) | 718 (43.5%) | 552 (42.9%) |  |  |
 Senior school | 364 (21.2%) | 430 (22.5%) | 335 (20.3%) | 233 (18.1%) |  |  |
 College and above | 70 (4.1%) | 122 (6.4%) | 131 (7.9%) | 156 (12.1%) |  |  |
Income | ||||||
 Low | 898 (52.5%) | 929 (48.9%) | 497 (30.1%) | 321 (25.3%) | 493.08 | < 0.001 |
 Medium | 589 (34.4%) | 663 (34.9%) | 664 (40.2%) | 463 (36.4%) |  |  |
 High | 224 (13.1%) | 306 (16.1%) | 489 (29.6%) | 487 (38.3%) |  |  |
Currently smoking | ||||||
 Yes | 27 (1.6%) | 20 (1.0%) | 16 (0.9%) | 11 (0.8%) | 4.48 | 0.216 |
 No | 1708 (98.4%) | 1913 (99.0%) | 1669 (99.1%) | 1289 (99.2%) |  |  |
Alcohol drinking | ||||||
 Yes | 142 (8.4%) | 154 (8.1%) | 154 (9.4%) | 132 (10.3%) | 5.38 | 0.146 |
 No | 1542 (91.6%) | 1739 (91.9%) | 1481 (90.6%) | 1150 (89.7%) |  |  |
Nutrients intake | ||||||
Carbohydrate (g) | 305.0 ± 100.3 | 291.8 ± 106.1 | 271.9 ± 91.3 | 254.5 ± 95.9 | 235.46 | < 0.001 |
Carbohydrate (%E) | ||||||
 = AMDR | 789 (46.2%) | 867 (46.3%) | 812 (49.9%) | 595 (47.0%) | 164.97 | < 0.001 |
 < AMDR | 343 (20.1%) | 467 (24.9%) | 474 (29.1%) | 445 (35.2%) |  |  |
 > AMDR | 577 (33.8%) | 538 (28.7%) | 341 (21%) | 225 (17.8%) |  |  |
Fat (g) | 65.0 ± 35.8 | 66.5 ± 35.2 | 70.0 ± 45.4 | 68.0 ± 37.5 | 5.02 | 0.002 |
Fat (%E) | ||||||
 = AMDR | 590 (34.5%) | 562 (30.0%) | 503 (30.9%) | 367 (29.0%) | 107.33 | < 0.001 |
 < AMDR | 417 (24.4%) | 413 (22.1%) | 253 (15.6%) | 185 (14.6%) |  |  |
 > AMDR | 702 (41.1%) | 897 (47.9%) | 871 (53.5%) | 713 (56.4%) |  |  |
Protein (g) | 63.8 ± 25.1 | 61.8 ± 20.7 | 62.3 ± 20.3 | 61.5 ± 21.3 | 7.39 | 0.061 |
Protein (%E) | ||||||
 = AMDR | 1155 (67.6%) | 1289 (68.9%) | 1084 (66.6%) | 811 (64.1%) | 102.78 | < 0.001 |
 < AMDR | 307 (18.0%) | 311 (16.6%) | 213 (13.1%) | 134 (10.6%) |  |  |
 > AMDR | 247 (14.5%) | 272 (14.5%) | 330 (20.3%) | 320 (25.3%) |  |  |
Daily behaviors | ||||||
LTPA | ||||||
 Yes | 172 (9.9%) | 188 (9.7%) | 199 (11.8%) | 128 (9.8%) | 5.40 | 0.145 |
 No | 1563 (90.1%) | 1745 (90.3%) | 1486 (88.2%) | 1172 (90.2%) |  |  |
Sedentary time (h/day) | ||||||
Mean ± SD | 2.8 ± 2.0 | 2.8 ± 1.9 | 3.1 ± 2.3 | 3.3 ± 2.2 | 69.96 | < 0.001 |
 < 2 h | 635 (36.9%) | 636 (33.2%) | 454 (27.6%) | 316 (24.6%) | 66.01 | < 0.001 |
 ≥ 2 h | 1087 (63.1%) | 1282 (66.8%) | 1193 (72.4%) | 971 (75.4%) |  |  |
Sleep duration (h/day) | ||||||
Mean ± SD | 8.3 ± 1.1 | 8.2 ± 1.0 | 8.1 ± 1.0 | 8.0 ± 1.0 | 57.39 | < 0.001 |
 ≥ 8 h | 1397 (83.0%) | 1517 (80.9%) | 1277 (78.6%) | 977 (75.2%) | 23.94 | < 0.001 |
 < 8 h | 286 (17.0%) | 357 (19.1%) | 347 (21.4%) | 305 (23.5%) |  |  |
Central obesity indices | ||||||
WC (cm) | ||||||
Mean ± SD | 75.9 ± 8.8 | 76.3 ± 8.8 | 77.2 ± 9.4 | 78.4 ± 9.6 | 60.11 | < 0.001 |
 Normal | 1360 (78.4%) | 1502 (77.7%) | 1264 (75.0%) | 901 (69.3%) | 40.10 | < 0.001 |
 High | 375 (21.6%) | 431 (22.3%) | 421 (25.0%) | 399 (30.7%) |  |  |
WHtR | ||||||
Mean ± SD | 0.5 ± 0.1 | 0.5 ± 0.1 | 0.5 ± 0.1 | 0.5 ± 0.1 | 46.28 | < 0.001 |
 Normal | 1339 (77.2%) | 1492 (77.2%) | 1247 (74.0%) | 876 (67.4%) | 48.69 | < 0.001 |
 High | 396 (22.8%) | 441 (22.8%) | 438 (26.0%) | 424 (32.6%) |  |  |