Feeding should be individualized in the critically ill patients.

Any critical care therapy requires individual adaptation, despite standardization of the concepts supporting them. Among these therapies, nutrition care has been repeatedly shown to influence clinical outcome. Individualized feeding is the next needed step towards optimal global critical care. Both underfeeding and overfeeding generate complications and should be prevented. The long forgotten endogenous energy production, maximal during the first 3 to 4 days, should be integrated in the nutrition plan, through a slow progression of feeding, as full feeding may result in early overfeeding. Accurate and repeated indirect calorimetry is becoming possible thanks to the recent development of a reliable, easy to use and affordable indirect calorimeter. The optimal timing of the prescription of the measured energy expenditure values as goal remains to be determined. Optimal protein prescription remains difficult as no clinically available tool has yet been identified reflecting the body needs. Although energy expenditure can now be measured, we miss indicators of early endogenous energy production and of protein needs. A pragmatic ramping up of extrinsic energy provision by nutrition support reduces the risk of overfeeding-related adverse effects.