The Beneficial Effects of Weight Reduction in Overweight Patients With Chronic Proteinuric Immunoglobulin A Nephropathy: A Randomized Controlled Trial

Abstract

This study was conducted to examine the effects of weight reduction on proteinuria, adipokines, and renal function in overweight immunoglobulin A nephropathy (IgAN) patients (body mass index > 23 kg/m2) with chronic proteinuria more than 6 months. This was a single-center, prospective, randomized controlled trial. The study was performed at the outpatient clinic at King Chulalongkorn Memorial Hospital, Bangkok, Thailand, from July 2012 to February 2013. Twenty-six overweight patients with chronic proteinuric biopsy-proven IgAN were randomized into a control group (n = 13) or a low-calorie normal protein diet group (n = 13). All patients received the maximum dosage of angiotensin-converting enzyme inhibitor or angiotensin receptor blocker and other antihypertensive agents to achieve a blood pressure less than 125/75 mmHg. The study intervention was a low-calorie diet (target energy per day as 500-kcal subtraction from total energy requirement) for a 6-month period. At baseline and after 6 months of a low-calorie diet, body weight, body content, and clinical and laboratory parameters were determined and compared. After initiating a low-calorie diet for 6 months, the normalized protein nitrogen appearance values were not different, indicating comparable protein intake. The low-calorie group had lower total daily calorie intake (1,307.1 ± 171.8 vs. 1,772.2 ± 315.4 kcal/d, P < .01) and significant reductions in body weight (-5.1 ± 3.3%, P < .001), fat content (-12.7 ± 14.1%, P < .05), and 24-hour urine protein (-45.2 ± 15.4%, P < .001). Blood pressure and renal function parameters were unaltered. The low-calorie group had approximately 20% lower plasma levels of leptin but unchanged adiponectin. There were positive correlations between the amount of protein reduction and the changes of body weight, fat mass, and leptin. A 6-month low-calorie diet leads to weight reduction and results in diminished fat content and decreased proteinuria in overweight IgAN patients with chronic proteinuria. This beneficial effect might be mediated by changes in adipokines.