Nutrition and Obesity Impacts on Kidney Health.

Clinical Background and Epidemiology: Nutrition and obesity are both important and common clinical issues in chronic kidney disease (CKD). Protein-energy wasting predicts adverse clinical outcomes in CKD. Obesity is associated with poor health outcomes. Nutrition management, specifically a protein-restricted diet, has been shown to ameliorate glomerular injury and progressive CKD by reducing glomerular hyperfiltration and hypertension. A protein-restricted diet has favorable metabolic and hemodynamic effects and effects on CKD-mineral bone disease that may favorably impact patients' outcomes. On the other hand, obesity may adversely affect kidney function both directly by placing an increased metabolic demand on the kidneys and indirectly through various humoral mechanisms mediated via adiponectin, leptin, and resistin that lead to hyperinsulinemia, insulin resistance, abnormal lipid metabolism, activation of renin-angiotensin aldosterone system, chronic inflammation, and oxidative stress, and could result in the development of obesity-related glomerulopathy. It is therefore important to raise more awareness of the two clinical issues and promote a healthy lifestyle with proper nutrition and exercise in CKD management. Challenges and Solutions: There are global shortage of dietitians and challenges in accessibility and availability of renal dietitians in many emerging countries as well as lack of reimbursement of dietitians' consultations. Many patients may not have the opportunity to be monitored and reviewed by dieticians on a regular basis. In addition, there are practical challenges in enforcing patients' adherence to a protein-restricted diet. Patients and nephrologists from developed countries may\not appreciate the need to adopt a protein restricted diets as dialysis is readily available. Furthermore, keto-analogues or nutrition supplements are not reimbursed in many parts of the world. Increased government advocacy, prioritization of renal nutrition care, and more trained renal dietitians are required in many parts of the world. More government resource allocation is required to increase renal dietitians' manpower in nephrology centers so to enable multidisciplinary nutrition management in CKD and end-stage kidney disease. On the other hand, prevention and treatment of obesity require lifestyle modifications including calorie restriction and adequate exercise, and they need to be maintained lifelong. Such changes may be difficult in modern societies with the "fast food culture" and increasing prevalence of sedentary lifestyles. Changes in lifestyle may become even more difficult as long-term complications such as diabetes and cardiovascular disease set in, which may further limit patients' mobility. To tackle the obesity epidemic, we need a global action plan to prevent and control non-communicable diseases. We need a concerted population-wide intervention by national governments, health policy planners, and professional organizations to target obesity and CKD by promoting healthy lifestyle factors and healthy diets. Pharmacologic and surgical interventions such as bariatric surgery for obesity require further evaluation in CKD.