Assessing body composition and energy expenditure in ICU.

Purpose of review: The "One Size fits All" nutritional approach, mainly using the patient's weight, has been challenged by recent progress allowing healthcare professionals to better define energy needs and determine body composition.

Recent findings: The Global Leadership Initiative on Malnutrition (GLIM) assessment has been recognized as a reliable tool for diagnosing malnutrition in the ICU. Complementing this approach, advancements in techniques for evaluating lean muscle mass, such as dual-energy biomarkers and computed tomography (CT), have improved the accuracy of muscle mass determination. When conducted by experienced practitioners, ultrasound offers a fast, reliable, and reproducible method for assessing muscle mass. Additionally, bioelectrical impedance analysis (BIA) has benefited from technological and methodological improvements, allowing the use of body cell mass as a guide for protein administration. Energy expenditure is most accurately measured using indirect calorimetry, which should be performed regularly due to day-to-day fluctuations and prevent the risks of overfeeding or underfeeding.

Summary: All these progresses are paving the way to precision nutrition in intensive care, determining more accurately the energy needs and adapting the macronutrient administration according to body composition and not anymore by kilogram weight.