Inclusion Criteria:  Invasive mechanical ventilation via a cuffed endotracheal or tracheotomy tube. Expected survival of ICU admission. Adults (≥18 years). Multi-organ failure (Sequential Organ Failure Assessment Score [SOFA] score ≥2 in 2 or more domains).  Exclusion Criteria:  Moribund or expected withholding treatment within 48 hours as judged by the investigator. Palliative goals of care. Contraindication for enteral nutrition. Pregnancy. Known severe musculoskeletal or neurological disability. Diabetic ketoacidosis. Phenylketonuria. BMI ≤17 or deemed malnourished as judged by the investigator. BMI >40.