Waist-to-height ratio (WtHR): proposed approach to establishing reference values for children and youths
Detection of central obesity is usually based on the criterion represented by the waist-to-height ratio (WtHR)≥ 0.50. However, that criterion has been disputed, especially in the period of growth. Since obesity cannot be reasonably defined without involving body fat content (%F), the aim of the study was to establish gender- and age-specific reference WtHR values for children and youths selected for an acceptable %F. In cohorts of 1193 boys and 1307 girls, aged 7–20 years, body fat content was determined from 3 skinfolds (triceps, subscapular, abdominal) using Slaughter’s equations. Next, 505 boys and 396 girls with acceptable fat percentage were selected and for them log WtHR values were computed. The equations for log WtHR values vs. age (a) were: (–0.31–0.01264a+0.000476a2)±0.0283 for boys and (–0.268–0.02047a+0 .00073a2)±0.0344 for girls. Upper WtHR limits (means +2SD) attained minimum values (0.460 and 0.454) in the age range of 12–15 years. When applying that criterion to subjects with excessive %F, 14.3% of all boys and 18.2% of girls were classified as centrally obese, but only 8.5 and 9.3%, respectively, when the WtHR=0.50 criterion alone was used. Cut-off values for WtHR indicating central obesity are markedly lower than 0.50 especially in the adolescence period and can be applied only to subjects with excessive fat percentage.
The study was partly supported by grants No. AWF-DS.153 and AWF-DM.10 of the Polish Ministry of Science and Higher Education.
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