A well known inverse relationship exists between obesity and circulating ghrelin concentrations. However, obesity is a heterogeneous disease entity and upper-body obesity (UBO) is associated with more profound metabolic disturbances than lower-body obesity (LBO). We therefore aimed to investigate the impact of body composition on circulating ghrelin levels in women spanning a wide range of body composition phenotypes.
Subjects and methods
Ten (UBO; waist-to-hip ratio (WHR) >0.85, body mass index (BMI) >28 kg/m2), ten LBO (WHR <0.80, BMI >28 kg/m2) and ten lean women (BMI<25 kg/m2) were studied. Total ghrelin levels were measured under basal and hyperinsulinemic (0.6 mU/kg per min) conditions. Body fat distribution was determined by dual X-ray absorptiometry in combination with computed tomography at the L2-L3 level.
As expected, an inverse correlation existed between basal ghrelin concentration and BMI (r=−0.40, P=0.03) and total fat mass (r=−0.39, P=0.04). Visceral fat mass was a strong predictor (r=−0.56, P=0.003) of circulating ghrelin levels, even when adjusted for BMI (P=0.02) or body composition group (P=0.04). The suppressive effect of insulin on ghrelin concentration was significantly diminished in the UBO compared with the lean controls (P=0.012) and a highly significant inverse correlation existed with visceral fat mass (r=−0.52, P=0.004).
Visceral fat mass is a strong predictor of basal ghrelin concentrations and also attenuates the suppressive effect of insulin on ghrelin concentrations. These data provide further evidence that the UBO phenotype is associated with more profound metabolic abnormalities than obesity per se.