Effects of weight loss on renal function in obese CKD patients: a systematic review.

Obesity is an independent risk factor for the development and progression of chronic kidney disease (CKD). We conducted a systematic review to assess the benefits of intentional weight loss in obese subjects with altered glomerular filtration rate (GFR), proteinuria or albuminuria. MEDLINE, EMBASE and CENTRAL databases were searched for articles reporting longitudinal data on the effect of weight loss on renal parameters in obese patients with altered kidney function. Thirty-one (2013 subjects) were included. In the 13 studies where weight loss was achieved by bariatric surgery, body mass index (BMI) significantly decreased in all studies; GFR decreased in six studies on hyperfiltration patients and increased in one study on patients with CKD Stage 3-4. Albuminuria decreased in six studies and proteinuria decreased in five studies. In six studies, weight loss was achieved by antiobesity agents: BMI decreased in all studies; GFR decreased in four studies and albuminuria in three. Eleven studies analysed the effects of diet, alone or in combination with lifestyle modifications. A significant decrease in BMI was reported in all studies; GFR increased in two studies, remained stable in four studies and decreased in two studies on hyperfiltration patients. Albuminuria decreased in six studies and remained stable in one study. Proteinuria decreased in five studies. In obese patients with altered renal function, weight loss, particularly if achieved by surgical interventions, improves proteinuria, albuminuria and normalizes GFR. Larger, long-term studies are needed to analyse the durability of this improvement and the effects on renal outcomes, such as CKD progression and the development of ESKD.