Introduction

Current recommendations on dietary energy intake (FAO/WHO/UNU, 1985; National Research Council, 1989) define expected average amounts of metabolizable energy required for sustaining normal metabolic processes, together with desirable or expected levels of physical activity in healthy individuals. In weight-stable adults, energy requirements are thus equal to total energy expenditure (TEE). In re-evaluating the energy requirements of older individuals, several key issues need to be addressed:

1. Traditionally, TEE has been estimated by a factorial approach involving summation of all the expected components of energy expenditure, taking into account the energy costs of different activities and their durations. Does this approach remain the most suitable method, or alternatively should requirements now be based on more direct measurements of TEE determined by the doubly labeled water technique? An additional methodological issue is whether the current procedure of expressing requirements as multiples of predicted resting energy expenditure (pREE) should be recommended for continuing use, i.e. the PAL (physical activity level) system.
2. Do current recommendations on the energy requirements of older individuals accurately predict usual energy needs for persons in each decade over 50 years of age?
3. What is the relationship between physical activity and energy requirements in older individuals?