Objectives: There is a limited knowledge concerning energy requirements of the elderly, especially the oldest old (>80 yr). Energy requirements should be estimated from measurements of energy expenditure.
Design and methods: 21 free-living individuals (8 males, 13 females), 91-96 years of age, living in Göteborg, Sweden were studied by the doubly labelled water method (DLW) for measuring total energy and by a ventilated hood system for Resting metabolic rate (RMR).
Results: RMR averaged 5.36 (SD 0.71) MJ/d in females (n=12) and 6.09 (SD 0.91) MJ/d in males (n=8). Difference between measured RMR and predicted basal metabolic rate (BMR) (n=20) was 0.015 (SD 0.86) MJ/d (NS). Total energy expenditure (TEE) measured by DLW averaged 6.3 (SD 0.81) MJ/d in females and 8.1 (SD 0.73) MJ/d in males. Activity energy expenditure (AEE=TEE-RMR), thus including diet induced thermogenesis, DIT) averaged 0.95 (SD 0.95) MJ/d in females (n=12) and 2.02 (1.13) MJ/d in males. Physical activity level (PAL=TEE/BMR) averaged 1.19 (SD 0.19) in females and 1.36 (SD 0.21)(p=0.08) in males.
Discussion: If DIT is assumed to be 10 per cent of TEE, energy spent on physical activity will be very low in this very old population.