Creatine kinase in relation to body fat in a Caucasian overweight and obese population.

We investigated the association between serum creatine kinase (CK) and body fat mass in an overweight and obese population. In this cross-sectional study, 454 Caucasian overweight and obese individuals recruited from a medical outpatient clinic and via newspaper advertising underwent dual-energy X-ray absorptiometry (DEXA). Serum CK was obtained along with supplementary blood samples. This report is based on a secondary analysis from a previous randomized controlled trial treating obesity with vitamin D3. Serum CK correlated negatively with body fat mass in men (r = -.18, p = .025) but not in women (r = -.11, p = .069). An insignificant negative trend for logCK across quartiles of fat mass in men was found (p = .098). CK did not associate significantly with lean mass, but lean mass correlated positively with fat mass in both groups (p < .0001). In a multivariate model, serum CK was inversely and independently related to fat mass in men. Fat mass decreased with 7.83 kg per unit logCK increase when adjusted for age and lean mass (95% CI -12.3 to -3.3, p = .001). These data support the view that circulating CK interacts with obesity in a favourable way independent of its muscular connection in men. CK was not associated with fat mass in women.