In order to avoid the adverse impacts of under-and over-feeding in hospitalised older patients, especially those receiving artificial nutritional support such as tube feeding or parenteral nutrition, the estimation of nutritional requirements is a vital component of the dietitian's assessment. While a number of international organisations recommend that energy expenditure is measured by indirect calorimetry in clinical practice, this is rarely practical or affordable, and dietitians are required to use one of a number of estimation methods e.g. factorial method, regression equations or the rule of thumb method (e.g. kcal/kg body weight). Each method has its relevant strengths and weaknesses which will be discussed during this presentation.