1995). As humans increase in weight and fatness from infancy to
adulthood, energy requirements increase as a power function
(BW0.63) of body weight. The capabilities of aging people need
not diminish if they maintain a healthy, active lifestyle.
Energy requirements and EE of healthy, active older people
(63-77 years) and younger people (average, 28 years) were
reported in a study of men receiving a diet with a defined
formula for 47 days under controlled conditions. Energy
expenditure while they were at rest: 1.22 × BMR, and while
sitting quietly: 1.30 × BMR, were the same for older and younger
men (Calloway and Zanni, 1980). Moderate activity, such as
walking on the level at about 2.5 mph, cost 4.51 ± 0.34 (mean ±
SD) kcal·min-1 (about 1.4 × BMR). Cycling at a comfortable load
(300-400 kpm) cost only slightly more energy than did walking
for both age groups. Metabolizable energy intake required to
maintain a constant BW for these men, who were sedentary except
for 30 min of cycling per day, was 2,554 ± 222 k