Beneficial effects of weight loss in overweight patients with chronic proteinuric nephropathies.

Proteinuria is a recognized complication of obesity, but no study has investigated the effect of weight loss in overweight patients with chronic proteinuric nephropathies of different causes. We randomly assigned (in a 2:1 ratio) 30 overweight patients (body mass index [BMI] > 27 kg/m(2)) with diabetic and nondiabetic proteinuric nephropathies to either follow a low-calorie normoproteinic diet or maintain their usual dietary intake for 5 months. The primary outcome was change in urinary protein excretion. Secondary outcomes were changes in renal function (serum creatinine level and Cockcroft-Gault creatinine clearance) and lipid profile. Patients in the diet group showed a significant decrease in body weight and BMI, whereas patients in the control group showed a significant increase in body weight and BMI (between-group comparison, P < 0.05). Mean weight loss in the diet group was 4.1% +/- 3%, and 14 of 20 patients in this group lost more than 3%. Proteinuria decreased by 31.2% +/- 37% in the diet group (from protein of 2.8 +/- 1.4 to 1.9 +/- 1.4 g/24 h; P < 0.005), whereas it tended to increase in the control group (between-group comparison, P < 0.05). Changes in renal function did not differ significantly between groups, although renal function remained stable in the diet group and showed significant worsening in the control group. Serum triglyceride levels remained stable in the diet group and tended to increase in the control group (between-group comparison, P < 0.05). Moderate weight loss in overweight patients with chronic proteinuric nephropathies induces a significant decrease in proteinuria. Am J Kidney Dis 41:319-327. Copyright 2003 by the National Kidney Foundation, Inc.