Overview
Appetite is the subjective drive or desire to eat that motivates food intake. It overlaps with but is not identical to the physiological sensation of hunger; appetite includes sensory, emotional and learned responses to food as well as homeostatic signals. Both humans and animals have appetite mechanisms that evolved to maintain energy balance and survival. For a basic definition see this summary.
Physiology and regulation
Appetite is regulated by interactions between the brain (notably the hypothalamus and reward circuits), the gastrointestinal tract and hormones such as ghrelin and leptin. Neural pathways integrate signals about nutrient status, stomach fullness and the sensory appeal of food to produce the feeling of wanting to eat. The physiological sensation commonly called hunger is one part of this system; further reading about hunger is available here.
Common influences and causes of change
Many factors alter appetite. Acute illness, chronic disease, emotional states, sleep patterns and certain medications can reduce or increase desire for food. Psychological conditions and eating disorders affect appetite as well: a loss of appetite is sometimes called anorexia, which should be distinguished from the psychiatric condition anorexia nervosa that involves complex behavioral and body-image features. Information about eating disorders in general is available here. Veterinary and comparative perspectives discuss appetite in nonhuman species here.
Consequences and management
Persistent increases in appetite can lead to excessive calorie intake and weight gain; long-term imbalance contributes to overweight and obesity. Conversely, a chronically low appetite may cause weight loss, malnutrition or frailty. Management focuses on identifying and treating underlying causes, nutritional counseling, behavioral strategies and, where appropriate, medical therapies. Some medications directly affect appetite; consult sources on drug effects here and on nutrition consequences here.
Practical notes and distinctions
- Appetite is influenced by environmental cues: time of day, social context and food presentation.
- Ageing and chronic illness commonly reduce appetite; this has implications for care and quality of life.
- Appetite differs from craving and satiety: cravings are intense desires for specific foods, while satiety is the sensation that ends eating.
Understanding appetite requires integrating biology with psychology and culture. For concise external introductions and resources, follow the links above to explore definitions, clinical issues and comparative perspectives.