NHANES (CDC), derived WHtR percentiles
About this reference
NHANES collects waist circumference (BMXWAIST) and standing height (BMXHT) in the same examination. FitnessNorms merged the August 2021-August 2023 body-measures and demographics files, retained adults aged 20 and older with positive measurements and MEC weight, excluded known pregnancies, calculated BMXWAIST divided by BMXHT, and computed weighted empirical P5, P25, P50, P75, and P95 values in sex-specific 5-year age groups plus 80 and older. The final sample is 5,718 adults and the smallest cell contains 136 people. An earlier version pooled 2015-2016, 2017-March 2020, and 2021-2023 and checked only medians. Review found that dividing every release weight by three was a common scalar, not equal-cycle weighting. The sensitivity pool was rebuilt using observation-period fractions of 2/7.2, 3.2/7.2, and 2/7.2, following CDC's duration-weighting principle. Comparing all 130 published quantiles found 12 cells with differences greater than 0.02 after rounding, with a maximum of 0.066. The reviewed page therefore uses the latest release alone; the multi-cycle output is retained only as sensitivity evidence. The weighted quantile uses linear interpolation on the midpoint cumulative-weight positions. Survey weights are applied for point estimates, but strata, clusters, and survey-design standard errors are not estimated. These are transparent FitnessNorms derivations, not official CDC statistics.
Known limitations
- US civilian noninstitutionalised population only; percentile position may differ in populations with different body-size distributions.
- This is an internal derivation by FitnessNorms from CDC public microdata, not a peer-reviewed publication. Weighted empirical quantiles are used; survey-design-correct standard errors are not reported.
- The reviewed table uses one NHANES release. Its smallest sex-by-age cell contains 136 people, so tail percentiles are less stable than central percentiles.
- Known pregnancies reported in RIDEXPRG are excluded. Public pregnancy status is limited to women aged 20-44, although NHANES suppresses body measures for several known pregnant participants outside that range.
- The August 2021-August 2023 examination response rate was 25.6%; NCHS adjusted weights for nonresponse, but subgroup precision may be lower than in earlier cycles.
- RIDAGEYR is top-coded at 80 in public data. The 80+ trend point at age 85 is a display anchor, not a mean observed age.
- Waist was measured at the NHANES iliac-crest site. Values measured at the navel, narrowest waist, or WHO midpoint are not directly interchangeable.
- Cross-sectional design: values reflect population averages at the time of survey, not individual trajectories.