Age-related changes in spontaneous food intake and hunger in humans.

Elderly people eat less than younger individuals. The nature of the changes in the meal pattern that occur with age were investigated by having 307 healthy adults, ages 20 to 80, maintain 7-day diaries of everything they ingested, the timing and conditions present, and subjective hunger, anxiety, depression, and activity. The lower intakes that occur with age were a consequence of the ingestion of smaller meals, eaten relatively slowly. The elderly were as responsive as younger subjects to a number of influences on intake, the time of day, the number of other people present, the subjective state of hunger, and the premeal contents of the stomach. These results suggest that the lower intakes in the elderly are a normal response to lower caloric expenditures. The state of hunger in the elderly affected intake equivalently to the young but intake did not affect hunger to the same extent as in younger subjects. This suggests that the internal state becomes less able to influence the subjective state as aging progresses and as a result the intake of the elderly may become primarily influenced by external factors.