Appetite

[1] Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs.

Poor appetite (anorexia) can have numerous causes, but may be a result of physical (infectious, autoimmune or malignant disease) or psychological (stress, mental disorders) factors.

Anorexia nervosa is a mental disorder characterized as severe dietary restriction and intense fear of weight gain.

Individuals who have anorexia have high levels of ghrelin, a hormone that stimulates appetite, so the body is trying to cause hunger, but the urge to eat is being suppressed by the person.

Body dysmorphic disorder may involve food restriction in an attempt to deal with a perceived fault, and may be associated with depression and social isolation.

A more recent addition is sibutramine which increases serotonin and noradrenaline levels in the central nervous system, but had to be withdrawn from the market when it was shown to have an adverse cardiovascular risk profile.

Similarly, the appetite suppressant rimonabant (a cannabinoid receptor antagonist) had to be withdrawn when it was linked with worsening depression and increased risk of suicide.

Recent reports on recombinant PYY 3-36 suggest that this agent may contribute to weight loss by suppressing appetite.

Given the epidemic proportions of obesity in the Western world and the fact that it is increasing rapidly in some poorer countries, observers[who?]

Rikkunshito, a traditional Japanese Kampo medicine, is under preliminary research for its potential to stimulate ghrelin and appetite.