Eating (also known as consuming) is the ingestion of food. In biology, this is typically done to provide a heterotrophic organism with energy and nutrients and to allow for growth. Animals and other heterotrophs must eat in order to survive — carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter, and detritivores eat detritus. Fungi digest organic matter outside their bodies as opposed to animals that digest their food inside their bodies.
For humans, eating is more complex, but is typically an activity of daily living. Physicians and dieticians consider a healthful diet essential for maintaining peak physical condition. Some individuals may limit their amount of nutritional intake. This may be a result of a lifestyle choice: as part of a diet or as religious fasting. Limited consumption may be due to hunger or famine. Overconsumption of calories may lead to obesity and the reasons behind it are myriad, however, its prevalence has led some to declare an "obesity epidemic".