Nutrition therapy is an essential aspect of patient care and an important determinant of outcomes in the ICU. Nutrition can impact respiratory function in a myriad of ways. Under- and overfeeding are two well-established ways by which nutrition impinges on respiratory function. Route of feeding, method of feeding, and carbohydrate composition of the diet are also other key factors regarding nutrition that influence outcomes in ICU patients. Recent studies are now elucidating the role of immune therapy in patients with acute respiratory distress syndrome. In the ICU, nutrition dogmas, such as the necessity of checking gastric residual volumes or utilizing full-calorie enteric feeds, as opposed to trophic feeds, are constantly being challenged by innovative clinical studies. Basic research brings the prospect of testing new approaches for ICU patients, such as the use of antioxidants to prevent diaphragm weakness in these patients. In this review article, we evaluate the recent observational and randomized control trials to critically appraise the evidence regarding nutrition in the ICU.