Dietary modification in chronic kidney disease (CKD) aims to reduce metabolic waste accumulation, control fluid balance, and prevent electrolyte disturbances. As glomerular filtration rate (GFR) declines, the kidneys lose ability to excrete potassium, phosphorus, sodium, and nitrogenous waste products. Potassium restriction (typically 2,000-3,000 mg/day) prevents life-threatening hyperkalemia and cardiac arrhythmias. Phosphorus restriction (800-1,000 mg/day) prevents renal osteodystrophy and vascular calcification through secondary hyperparathyroidism. Sodium restriction (1,500-2,000 mg/day) controls hypertension and fluid retention. Protein restriction in pre-dialysis CKD (0.6-0.8 g/kg/day) reduces uremic toxin production, while dialysis patients require increased protein (1.2 g/kg/day) to replace losses. Fluid restriction depends on urine output and dialysis schedule.