Everyone agrees that providing adequate nutrition in critical illness is vitally important. The problem is, no one knows for sure what “adequate” means. Caloric targets are not based on evidence from randomized trials with meaningful clinical outcomes. They emerge as consensus from educated guesses by researchers conducting physiology studies. One camp believes that extra calories should be provided to counteract catabolism; another argues that illness-induced anorexia is adaptive and that a normal caloric load represents overfeeding.