Eating

Physicians and dieticians consider a healthful diet essential for maintaining peak physical condition.

"[2] At picnics, potlucks, and food festivals, eating is the primary purpose of a social gathering.

[6] Having three well-balanced meals (described as: half of the plate with vegetables, 1/4 protein food as meat, [...] and 1/4 carbohydrates as pasta, rice)[7] will then amount to some 1800–2000 kcal, which is the average requirement for a regular person.

Between 8 and 12 months of age, the digestive system improves, and many babies begin eating finger foods.

By 18 months, babies often have enough teeth and a sufficiently mature digestive system to eat the same foods as adults.

[19] Many laboratory studies showed that overweight individuals are more emotionally reactive and are more likely to overeat when distressed than people of normal weight.

Furthermore, it was consistently found that obese individuals experience negative emotions more frequently and more intensively than do normal weight persons.

The study confirmed the tendency of obese individuals to overeat, but these findings applied only to snacks, not to meals.

[24] When the glucose levels of cells drop (glucoprivation), the body starts to produce the feeling of hunger.

The body also stimulates eating by detecting a drop in cellular lipid levels (lipoprivation).

[24] The taste and odor of food can contribute to short-term satiety, allowing the body to learn when to stop eating.

[23] The brain stem can control food intake, because it contains neural circuits that detect hunger and satiety signals from other parts of the body.

Rats that have had the motor neurons in the brain stem disconnected from the neural circuits of the cerebral hemispheres (decerebration), are unable to approach and eat food.

These include depression, food allergies, ingestion of certain chemicals, bulimia, anorexia nervosa, pituitary gland malfunction and other endocrine problems, and numerous other illnesses and eating disorders.

While changes in appetite can result from various physical and psychological conditions, including depression, allergies, and anxiety; anorexia and bulimia are specific eating disorders that profoundly impact the entire body.

[31] Bulimia is characterized by recurrent episodes of binge eating, involving the consumption of a substantial amount of food within a short period.

Subsequently, individuals engage in maladaptive behaviors, such as inducing vomiting, excessive physical activity, and using laxatives as compensatory measures.

While the earliest mammals were probably predators, different species have since adapted to meet their dietary requirements in a variety of ways.

Exceptions to this include baleen whales who also house gut flora in a multi-chambered stomach, like terrestrial herbivores.

Mammals that weigh less than about 18 ounces (510 g; 1.1 lb) are mostly insectivorous because they cannot tolerate the slow, complex digestive process of an herbivore.

[39] Some mammals are omnivores and display varying degrees of carnivory and herbivory, generally leaning in favour of one more than the other.

Since plants and meat are digested differently, there is a preference for one over the other, as in bears where some species may be mostly carnivorous and others mostly herbivorous.

The dentition of hypocarnivores consists of dull, triangular carnassial teeth meant for grinding food.

Thus, such animals are still able to be classified as carnivores and herbivores when they are just obtaining nutrients from materials originating from sources that do not seemingly complement their classification.

[42] For example, it is well documented that some ungulates such as giraffes, camels, and cattle, will gnaw on bones to consume particular minerals and nutrients.

[43] Also, cats, which are generally regarded as obligate carnivores, occasionally eat grass to regurgitate indigestible material (such as hairballs), aid with haemoglobin production, and as a laxative.

[49] The digestive system of birds is unique, with a crop for storage and a gizzard that contains swallowed stones for grinding food to compensate for the lack of teeth.

[55] Nectar feeders such as hummingbirds, sunbirds, lories, and lorikeets amongst others have specially adapted brushy tongues and in many cases bills designed to fit co-adapted flowers.