The ‘fat but powerful’ paradox: association of muscle power and adiposity markers with all-cause mortality in older adults from the EXERNET Multi-center Study

ObjectivesTo assess the influence of muscle power and adiposity on all-cause mortality risk and to evaluate the ‘fat but powerful’ (or ‘fat but fit’) paradox in older adults.MethodsA total of 2563 older adults (65‒91 years old) from the EXERNET Multi-center study were included. Adiposity (body mass index (BMI), waist circumference, body fat percentage (BF%) and fat index), allometric and relative power (sit-to-stand muscle power test) and various covariates (age, sex, hypertension, smoking status, and walking and sitting times per day) were registered at baseline. All-cause mortality was recorded during a median follow-up of 8.9 years. Participants were classified into four groups: lean and powerful (L+P), fat but powerful (F+P), lean but weak (L+W) and fat and weak (F+W). Cox proportional hazard regression models and adjusted hazard ratios (HR) were calculated.ResultsAccording to BMI and waist circumference, all-cause mortality risk was reduced in the F+P (HR=0.55 and 0.63, respectively; p≤0.049) and L+P (HR=0.57 and 0.58, respectively; p≤0.043) groups. According to BF%, all-cause mortality decreased in the L+P group (HR=0.53; p=0.021), and a trend for a reduction was reported in the F+P group (HR=0.57; p=0.060). According to fat index, a survival benefit was only noted in the L+P group (HR=0.50; p=0.049). Higher levels of relative power reduced all-cause mortality risk among older people (HR=0.63 and 0.53, respectively; p≤0.011).ConclusionPowerful older people exhibited a reduced 9-year all-cause mortality regardless of BMI, waist circumference and BF%. Obesity according to fat index blunted the survival benefits of being powerful.