Healthy obesity and risk of accelerated functional decline and disability

BACKGROUND/OBJECTIVES: Some obese adults have a normal metabolic profile and are considered ‘healthy', but whether they experience faster ageing than healthy normal-weight adults is unknown. We compared decline in physical function, worsening of bodily pain and likelihood of future mobility limitation and disability between these groups. SUBJECTS/METHODS: This was a population-based observational study using repeated measures over 2 decades (Whitehall II cohort data). Normal-weight (body mass index (BMI) 18.5–24.9 kg m(−)(2)), overweight (25.0–29.9 kg m(−)(2)) and obese (⩾30.0 kg m(−2)) adults were considered metabolically healthy if they had 0 or 1 of 5 risk factors (hypertension, low high-density lipoprotein cholesterol, high triacylglycerol, high blood glucose and insulin resistance) in 1991/1994. Decline in physical function and worsening of bodily pain based on change in Short Form Health Survey items using eight repeated measures over 18.8 years (1991/1994–2012/2013) were compared between metabolic-BMI groups using linear mixed models. Odds of mobility limitation based on objective walking speed (slowest tertile) and of disability based on limitations in ⩾1 of 6 basic activities of daily living, each using three repeated measures over 8.3 years (2002/2004–2012/2013), were compared using logistic mixed models. RESULTS: In multivariable-adjusted mixed models on up to 6635 adults (initial mean age 50 years; 70% male), healthy normal-weight adults experienced a decline in physical function of −3.68 (95% CI=−4.19, −3.16) score units per decade; healthy obese adults showed an additional −3.48 (−4.88, −2.08) units decline. Healthy normal-weight adults experienced a −0.49 (−1.11, 0.12) score unit worsening of bodily pain per decade; healthy obese adults had an additional −2.23 (−3.78, −0.69) units worsening. Healthy obesity versus healthy normal-weight conferred 3.39 (2.29, 5.02) times higher odds of mobility limitation and 3.75 (1.94, 7.24) times higher odds of disability. CONCLUSIONS: Our results suggest that obesity, even if metabolically healthy, accelerates age-related declines in functional ability and poses a threat to independence in older age.