The effect of time-restricted feeding on renal function in patients with intermediate-advanced stage chronic kidney disase

Introduction: Chronic kidney disease (CKD) is a global public health problem and it was determined that 697.5 million people globally had CKD and its prevalence was 9.1% in 2017. It is emphasised that the development and progression of CKD can be slowed down when important risk factors such as obesity, diabetes and hypertension are controlled [1] [2]. Lifestyle changes and nutrition have an important place in the treatment of CKD. In various studies, it has been determined that calorie restriction may have favourable effects in the prevention of CKD development and progression [3]. Intermittent calorie restriction practices known as intermittent fasting (IF), which have been widely studied and discussed in recent years, are nutritional strategies that recommend feeding between certain periods of time and restrict feeding times rather than food variety and quality. Time-Restricted Feeding (TRF) which is considered as a subgroup of IF practice, does not require calorie restriction but requires feeding on certain time of a day. In addition to weight loss, intermittent fasting practices have been found to have anti-inflammatory and anti-oxidant effects, reduce anabolic processes (synthesis, growth and reproduction), support cellular maintenance and repair systems, increase the stress resistance of cells and recycle damaged molecules [4], [5] . Therefore, we think that time-restricted feeding in CKD, could slow down the progression of disease and may help to sustain residual renal function. In this study, we investigated the effect of time-restricted feeding on renal function in patients with intermediate-advanced stage CKD. Material and Method: Eighty-four patients aged 18-70 years with stage 3-5 chronic kidney disease were included in the study and divided into two groups. The study group consisted of patients on time-restricted feeding (TRF) without calorie restriction (n=42) and the control group consisted of patients on free feeding (FF) (n=42). Baseline measurements of height, weight, waist circumference, blood pressure and routine biochemical parameters including e GFR, CRP values and urine protein creatinine ratio were recorded. These measurements of the patients were re-evaluated at follow-up visits twice, at the 3rd and 6th months. Results: According to the six-month follow-up results, there was no statistically significant change in renal function evaluated by urea, creatinine and eGFR levels in the TRF group and the renal function remained at constant levels (p=0.07). On the other hand, there was a significant decrease and regression in renal function in the SB group (p<0.01). Changes in eGFR, urea and creatinine measurements did not differ significantly between the groups except for changes in urine protein-creatinine ratio (p=0.04). In addition, a significant decrease in waist circumference measurements was observed in the TRF group (p<0.01). There were no statistically significant changes in weight, body mass index measurements, CRP values and urine protein creatinine ratios in the participants of both groups during the follow-up period. Conclusion: Time-restricted feeding for six months in patients with moderate to advanced CKD not receiving renal replacement therapy may have a protective effect on renal function and may contribute to the treatment of central obesity. Keywords: Chronic kidney disease, Time-restricted feeding, Intermittent fasting, CKD, TRF, eGFR.