Eating 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.
Appetite is the desire to eat food items, usually due to hunger. Appealing foods can stimulate appetite even when hunger is absent, although appetite can be greatly reduced by satiety. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Appetite has a relationship with every individual's behavior. Appetitive behaviour also known as approach behaviour, and consummatory behaviour, are the only processes that involve energy intake, whereas all other behaviours affect the release of energy. When stressed, appetite levels may increase and result in an increase of food intake. Decreased desire to eat is termed anorexia, while polyphagia is increased eating. Dysregulation of appetite contributes to anorexia nervosa, bulimia nervosa, cachexia, overeating, and binge eating disorder.
Weight gain is an increase in body weight. This can involve an increase in muscle mass, fat deposits, excess fluids such as water or other factors. Weight gain can be a symptom of a serious medical condition.
A food addiction or eating addiction is any behavioral addiction characterized primarily by the compulsive consumption of palatable and hyperpalatable food items. Such foods often have high sugar, fat, and salt contents, and markedly activate the reward system in humans and other animals. Those with eating addictions often overconsume such foods despite the adverse consequences associated with their overconsumption.
A food craving is an intense desire to consume a specific food, and is different from normal hunger. It may or may not be related to specific hunger, the drive to consume particular nutrients that is well-studied in animals. In studies of food cravings, chocolate and chocolate confectioneries almost always top the list of foods people say they crave; this craving is referred to as chocoholism. The craving of non-food items as food is called pica.
Palatability is the hedonic reward provided by foods or fluids that are agreeable to the "palate", which often varies relative to the homeostatic satisfaction of nutritional and/or water needs. The palatability of a food or fluid, unlike its flavor or taste, varies with the state of an individual: it is lower after consumption and higher when deprived. It has increasingly been appreciated that this can create a hunger that is independent of homeostatic needs.
Diet plays an important role in the genesis of obesity. Personal choices, food advertising, social customs and cultural influences, as well as food availability and pricing all play a role in determining what and how much an individual eats.
Obesity in pets occurs when excessive adipose tissue accumulates in the body, and is generally defined as occurring when an animal's body weight is at least 20% greater than its optimal body weight. Obesity is associated with metabolic and hormonal changes, and can predispose pets to illnesses like orthopedic disease, diabetes, and cancer.
In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake and energy expenditure. The human brain, particularly the hypothalamus, plays a central role in regulating energy homeostasis and generating the sense of hunger by integrating a number of biochemical signals that transmit information about energy balance. Fifty percent of the energy from glucose metabolism is immediately converted to heat.
Hunger is a sensation that motivates the consumption of food. The sensation of hunger typically manifests after only a few hours without eating and is generally considered to be unpleasant. Satiety occurs between 5 and 20 minutes after eating. There are several theories about how the feeling of hunger arises. The desire to eat food, or appetite, is another sensation experienced with regard to eating.
Weight management refers to behaviors, techniques, and physiological processes that contribute to a person's ability to attain and maintain a healthy weight. Most weight management techniques encompass long-term lifestyle strategies that promote healthy eating and daily physical activity. Moreover, weight management involves developing meaningful ways to track weight over time and to identify the ideal body weights for different individuals.
Robert H. Lustig is an American pediatric endocrinologist. He is Professor emeritus of Pediatrics in the Division of Endocrinology at the University of California, San Francisco (UCSF), where he specialized in neuroendocrinology and childhood obesity. He is also director of UCSF's WATCH program, and president and co-founder of the non-profit Institute for Responsible Nutrition.
Sleep is important in regulating metabolism. Mammalian sleep can be sub-divided into two distinct phases - REM and non-REM (NREM) sleep. In humans and cats, NREM sleep has four stages, where the third and fourth stages are considered slow-wave sleep (SWS). SWS is considered deep sleep, when metabolism is least active.
Satiety value is the degree at which food gives a human the sense of food gratification, the exact contrast feeling of hunger. The concept of the Satiety Value and Satiety Index was developed by Australian researcher and doctor, Susanna Holt. Highest satiety value is expected when the food that remains in the stomach for a longer period produces greatest functional activity of the organ. Limiting the food intake after reaching the satiety value helps reduce obesity problems.
Emotional eating, also known as stress eating and emotional overeating, is defined as the "propensity to eat in response to positive and negative emotions". While the term commonly refers to eating as a means of coping with negative emotions, it sometimes include eating for positive emotions, such as overeating when celebrating an event or to enhance an already good mood.
Hedonic hunger or hedonic hyperphagia is the "drive to eat to obtain pleasure in the absence of an energy deficit". Particular foods may have a high "hedonic rating" or individuals may have increased susceptibility to environmental food cues. Weight loss programs may aim to control or to compensate for hedonic hunger. Therapeutic interventions may influence hedonic eating behavior.
Sleep and weight is the association between the amount of sleep an individual obtains and the weight of that individual.
An ultra-processed food (UPF) is an industrially formulated edible substance derived from natural food or synthesized from other organic compounds. The resulting products are designed to be highly profitable, convenient, and hyperpalatable, often through food additives such as preservatives, colourings, and flavourings. UPFs have often undergone processes such as moulding/extruding, hydrogenation or frying.
Pathophysiology of obesity is the study of disordered physiological processes that cause, result from, or are otherwise associated with obesity. A number of possible pathophysiological mechanisms have been identified which may contribute in the development and maintenance of obesity.
The Nova classification is a framework for grouping edible substances based on the extent and purpose of food processing applied to them. Researchers at the University of São Paulo, Brazil, proposed the system in 2009.
