Hypocaloric feeding of the critically ill.

During critical illness, the stress response causes accelerated gluconeogenesis and lipolysis, leading to hyperglycemia and elevated serum triglyceride levels. The traditional nutrition support strategy of meeting or exceeding calorie requirements may compound the metabolic alterations of the stress response. Hypocaloric nutrition support has the potential to provide nutrition support without exacerbating the stress response. Studies have shown hypocaloric nutrition support to be safe and to achieve nitrogen balance comparable with traditional regimens. Benefits shown include improved glycemic control, decreased intensive care unit (ICU) length of stay (LOS), and decreased ventilator days and infection rate; however, not all studies have produced identical results. Providing adequate dietary protein has emerged as an important factor in efficacy of the hypocaloric regimen. Although it is inconclusive, currently available research suggests that a nutrition support goal of 10-20 kcal/kg of ideal or adjusted weight and 1.5-2 g/kg ideal weight of protein may be beneficial during the acute stress response. Well-designed, randomized, controlled studies with adequate sample size that evaluate relevant clinical outcomes such as mortality, ICU LOS, and infection while controlling for factors such as glycemic control, severity of illness, incorporation of calories from all sources, in addition to feeding regimens, are needed to definitively determine the effects of hypocaloric nutrition support.