Acute kidney injury is a frequent complication affecting many hospitalized patients and is associated with increased morbidity and mortality. Acute kidney injury often occurs in conjunction with critical illness, which is a hypermetabolic state presenting with hyperglycemia, insulin resistance, hypertriglyceridemia, and increased protein catabolism. In addition to addressing these changes, the clinician should evaluate the important nutrition implications of decreased kidney function. These include vitamins, electrolytes, minerals, trace elements, and the presence and type of renal replacement therapy. Optimal nutrition management in acute kidney injury includes providing adequate macronutrient support to correct underlying conditions and prevent ongoing loss, supplementing micronutrients and vitamins during renal replacement therapy, and adjusting electrolyte replacement based on the degree and extent of renal dysfunction.