Age is one of the most important factor of changes in energy metabolism.

The basal metabolic rate decreases almost linearly with age.

Skeletal musculature is a fundamental organ that consumes the largest part of energy in the normal human body. The total volume of skeletal muscle can be estimated by 24-hours creatinine excretion. The volume of skeletal musculature decreases and the percentage of fat tissue increases with age. It is shown that the decrease in muscle mass relative to total body may be wholly responsible for the age-related decreases in basal metabolic rate. Energy consumption by physical activity also decreases with atrophic changes of skeletal muscle.

Thus, energy requirement in the elderly decreases. With decrease of energy intake, intake of essential nutrients also decreases. If energy intake, on the other hand, exceeds individual energy needs…