A calorie deficit (

British English British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...

: calorific deficit) is any shortage in the number of

calories The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of o ...

consumed relative to the number of calories needed for maintenance of current body weight (

energy homeostasis In biology, energy homeostasis, or the homeostatic control of energy balance, is a biological process that involves the coordinated homeostatic regulation of food intake (energy inflow) and energy expenditure (energy outflow). The human brain, part ...

). A deficit can be created by decreasing calories consumed by lower food intake, such as by swapping high-calorie foods for lower calorie options or by reducing portion sizes. A deficit can also be created by increasing output (burning calories) without a corresponding increase in input. Increased output is created by increasing physical activity, from increased caloric requirements necessary to heal an injury, or from growth. There are also some substances, including

caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...

, which can create a small (3-5%) increase in caloric expenditure, via a variety of pathways that include increasing physical activity levels and increasing

thermogenesis Thermogenesis is the process of heat production in organisms. It occurs in all warm-blooded animals, and also in a few species of thermogenic plants such as the Eastern skunk cabbage, the Voodoo lily ('' Sauromatum venosum''), and the giant w ...

(heat output), and/or by reducing caloric input via appetite suppression. Drugs and

herbal A herbal is a book containing the names and descriptions of plants, usually with information on their medicinal, tonic, culinary, toxic, hallucinatory, aromatic, or magical powers, and the legends associated with them.Arber, p. 14. A herbal ...

treatments creating a more extreme metabolic effect exist; however, they cause extreme increases of heart rate and thermogenesis that can cause death in even very healthy and athletic individuals, and these drugs are not widely sold. As the calories required for

decreases as the organism's mass decreases, if a moderate deficit is maintained eventually a new (lower) weight will be reached and maintained, and the organism will no longer be at caloric deficit. A permanent severe deficit, on the other hand, which contains too few calories to maintain a healthy weight level, will eventually result in

starvation Starvation is a severe deficiency in caloric energy intake, below the level needed to maintain an organism's life. It is the most extreme form of malnutrition. In humans, prolonged starvation can cause permanent organ damage and eventually, dea ...

and death. To reduce 1 kg (2.2 lbs) of weight, about 7000 kcal deficit is required.

References

{{Reflist Weight loss

See also

References