To examine whether Health Canada's Recommended Nutrient Intakes (RNI) and FAO/WHO/UNU (Food and Agriculture Organization, World Health Organization, United Nations University) values provide accurate indices of true energy requirements, energy expenditure was determined using doubly labelled water (DLW) over 13 days in a group of 29 middle-aged women. Energy intakes were calculated from weighed food intake, and energy expenditures and intakes were then compared with individual calculated RNI requirements. The mean energy requirement as determined by DLW expenditure (9.56 +/- 0.53 MJ/d) was higher (p