Subcutaneous adipocyte size and body fat distribution.

BACKGROUND Both body fat distribution and adipocyte size are associated with metabolic abnormalities. OBJECTIVE We defined the extent to which subcutaneous adipocyte size is related to regional fat mass and to the sizes of adipocytes in other subcutaneous depots independent of adiposity, age, and sex. DESIGN Data collected from 188 women and 133 men who were 18-50 y old and who had a body mass index (in kg/m2) of 18 to 50 were analyzed. The mean size of isolated subcutaneous abdominal, femoral, and gluteal adipocytes was measured by direct microscopy or by automated analysis of digital images. Visceral fat area was measured with computed tomography. Dual-energy X-ray absorptiometry was used to calculate adiposity. RESULTS Stepwise multiple regression analyses showed that abdominal adipocyte size was associated positively with visceral and subcutaneous abdominal fat areas and negatively with lower-body fat mass as a percentage of total-body fat, after control for sex and percentage body fat. Femoral adipocyte size was related to percentage body fat (P<0.0001), whereas gluteal adipocyte size was related to visceral fat area (P=0.002), which suggests that these 2 lower-body fat depots are distinct. Analyses of data from a subset of volunteers (n=99) for whom we had adipocyte size from all 3 depots showed that adipocyte size from 1 depot could be better predicted if adipocyte size from other depots were known. CONCLUSIONS Abdominal adipocyte size is related to body fat distribution. Adipocyte size in a person seems to be globally regulated by factors independent of variations in body fat distribution.