Table 3.
Anthropometrics characteristics of the sample: adolescents aged 17–19 years, Johannesburg–Soweto, South Africa, Birth to Twenty Plus (Bt20+) cohort
| Total group (n 2019) | Men (n 974) | Women (n 1045) | |||||
|---|---|---|---|---|---|---|---|
| Variable | Mean or median | sd or IQR | Mean or median | sd or IQR | Mean or median | sd or IQR | Test |
| Height (cm) | 165·5 | 8·8 | 171·5 | 6·9 | 159·9 | 6·4 | P<0·0001***§ |
| Weight (kg) | 57·6 | 51·8–64·8 | 58·3 | 53·6–65·3 | 56·5 | 50·2–64·2 | P<0·0001***|| |
| BMI (kg/m2) | 20·8 | 19·0–23·5 | 19·9 | 18·5–21·7 | 22·0 | 19·8–25·1 | P<0·0001***|| |
| n | % | n | % | n | % | ||
| BMI in four classes† | |||||||
| Thinness | 327 | 16·2 | 216 | 22·2 | 111 | 10·6 | P<0·0001***¶ |
| Normal | 1338 | 66·3 | 678 | 69·6 | 660 | 63·2 | |
| Overweight | 245 | 12·2 | 59 | 6·1 | 187 | 17·9 | |
| Obese | 108 | 5·3 | 21 | 2·2 | 87 | 8·3 | |
| Overweight (including obesity) | 354 | 17·5 | 80 | 8·2 | 274 | 26·2 | P<0·0001***¶ |
| Overweight:thinness ratio | 1·1 | 0·4 | 2·5 | ||||
| Total group (n 1728) | Men (n 839) | Women (n 889) | |||||
| Variable | Mean | sd | Median | IQR | Mean | sd | Test |
| %BF | 23·8 | 11·7 | 12·05 | 9·9–15·3 | 33·2 | 7·11 | P<0·0001***|| |
| n | % | n | % | n | % | ||
| %BF in three classes‡ | |||||||
| Low %BF (≤15·00th percentile) | 626 | 36·2 | 501 | 59·8 | 125 | 14·0 | P<0·0001***¶ |
| Normal %BF (≥15·01 and ≤85·00th percentile) | 845 | 48·9 | 294 | 35·0 | 551 | 62·0 | P<0·0001***¶ |
| High %BF (≥85·01th percentile) | 257 | 14·9 | 44 | 5·2 | 213 | 24·0 | P<0·0001***¶ |
IQR, interquartile range; %BF, percentage body fat.
(*) P<0·10, *P<0·05, **P<0·01, ***P<0·001.
†
Categories of BMI were defined using age- and sex-specific international cut-offs for BMI for <18 years( 46 , 47 ) and ≥18 years( 48 ).
‡
Categories of %BF were defined using age- and sex-specific cut-off points based on the US Third National Health and Nutrition Examination Survey( 49 ).
§
P value from t test.
||
P value from Mann–Whitney test.
¶
P value from χ 2 test.