Large surveys auditing feeding regimen in the ICU consistently reported hypocaloric 23 enteral feedings patterns and many studies described the association between 24 energy deficit and increased complication rate. ESPEN and ASPEN experts 25 recommend early (after 48 h) or late (after 7-10 days) catch up of the 26 energy deficit with parenteral nutrition (PN) respectively, but the level of evidence 27 was poor and larger PRCT were missing. In the recent months, several ICU studies 28 have tried to answer to three critical questions: 1) how much energy to administer, 2) 29 when to start (early or late), and 3) which route should be used. However, weaknesses 30 in the study design and some mixing of the 3 questions have created confusion in the 31 message delivered. In addition, the severity of the acute illness was not always similar 32 in these studies, mixing short-term acutely ill patients (less than 4 days in the ICU) 33 with long term patients (more than 10 days in the ICU).