Trends in the prevalence of metabolically healthy and unhealthy obesity in the US adult population: analysis of eight NHANES cross-sectional survey cycles, 1999–2014

OBJECTIVE: To exam the time trend of the prevalence of metabolically healthy obesity (MHO) in the US adult population. DESIGN: Eight cross-sectional survey cycles. SETTING: National Health and Nutrition Examination Survey (NHANES), 1999–2014. PARTICIPANTS: 16 459 NHANES participants aged 20 years and older. PRIMARY OUTCOME MEASURE: MHO was defined as central obesity (waist circumference ≥102 cm for men and ≥88 cm for women) without any of the following conditions: elevated levels of blood pressure (≥130/85 mm Hg), glucose (≥100 mg/dL) and triglycerides (≥150 mm/dL); reduced levels of high-density lipoprotein cholesterol (<40 mg/dL for men and <50 mg/dL for women) or any medication use for high cholesterol, hypertension or diabetes. RESULTS: The prevalence of central obesity significantly increased from 45.2% in 1999–2000 to 56.7% in 2013–2014 (p=0.003). Over the same period, MHO prevalence among those with central obesity only slightly and non-significantly increased from 11.0% to 15.7% (p=0.38). However, MHO prevalence among women increased significantly (p=0.04) from 7.1% to 13.7%. Female gender, a younger age, being Hispanic and non-Hispanic black and high education (some college or above) were significantly (p<0.05) associated with higher prevalence of MHO. CONCLUSIONS: While the prevalence of central obesity in the US population has increased since 1999, the prevalence of MHO among those who are centrally obese remained fairly stable.