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.
[6][7] Drugs and 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.
[7][8] As the calories required for energy homeostasis 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.
[2] A permanent severe deficit, on the other hand, which contains too few calories to maintain a healthy weight level, will eventually result in starvation and death.
To reduce 1 kg (2.2 lbs) of weight, about 7000 kcal deficit is required.