Arjan Kwakernaak from the University Medical Center Groningen, The Netherlands and colleagues sought to find out whether or not central distribution of body fat was associated with a higher risk of renal disease, or if it was due to the excess weight overall. The study compared the waist-to-hip ratio (WHR), a measure reflecting central adiposity, and renal hemodynamics in 315 healthy persons with a mean body mass index (BMI) of 24.9kg/m^2 and a mean iodine 125-labeled iothalamate GFR of 109ml/min per 1.73m^2.

Results following multivariate analyses showed WHR was associated with lower GFR, lower effective renal plasma flow, and higher filtration fraction despite having adjusted for sex, age, mean arterial pressure, and BMI. Multivariate models expressed similar results even when hemodynamic measures were indexed to body surface area suggesting that central body fat distribution was associated with unfavorable renal hemodynamic measures."We found that apple-shaped persons -- even if totally healthy and with a normal blood pressure -- have an elevated blood pressure in their kidneys. When they are also overweight or obese, this is even worse," Kwakernaak said in an American Society of Nephrology news release. The authors conclude that the unfavorable renal hemodynamic measures associated with the central adiposity may be involved in the renal risk.