Satiety: an ecological perspective.

The frequency and size of meals in freely feeding animals vary as a function of the economic structure of the animals' niche and their habitat. This paper reviews some of the evidence supporting this proposition. When the cost of access to a meal increases, the frequency of meals decreases and their size increases compensatorily. Similarly, increasing the caloric density of a meal results in a decrease in both meal frequency and size. When foraging animals encounter opportunities to procure meals that differ in cost or in benefit, they almost always procure low-cost or high-benefit meals. The frequency with which they procure high-cost or low-benefit meals is a function of the magnitude of the difference between either the costs or the benefits of the meals they had an opportunity to procure. To feed optimally an animal must minimize the sum of the costs of foraging, consumption, and utilization and maximize the sum of benefits. To accomplish this, an animal must integrate information from its niche, its habitat, the process of ingestion, postingestive consequences, and its metabolic state. Feedback from both the consequences of ingestion and the metabolic state probably acts indirectly to provide information rather than directly as a satiety stimulus.