[Nutrition and the Kidney: Beyond Restriction].

Chronic kidney disease is a growing global health concern, driven by aging and comorbidities such as diabetes and hypertension. Proper nutrition is essential to slowing disease progression and reducing metabolic and cardiovascular complications. Protein-energy wasting is common in patients with CKD stages 4-5 and those on dialysis, associated with the accumulation of uremic toxins that trigger systemic inflammation, anorexia, acidosis, and muscle catabolism. Nutritional assessment should be a standard of care and conducted periodically, incorporating anthropometric parameters, biochemical markers, and imaging studies. The main phenotypes include loss of contractile muscle mass, protein-energy wasting, sarcopenia, and sarcopenic obesity. Management varies based on disease stage and comorbidities and includes the adjustment or restriction of macro- and micronutrients, nutritional supplements, structured physical activity, and, in some cases, intradialytic parenteral nutrition to improve nutritional status and clinical outcomes.