Autophagia refers to the practice of biting/consuming one's body. It is a sub category of self-injurious behavior (SIB). Commonly, it manifests in humans as nail biting and hair pulling. In rarer circumstances, it manifests as serious self mutilative behavior such as biting of one's fingers. Autophagia affects both humans and non humans. Human autophagia typically occurs in parts of the body that are sensitive to pain, such as fingers. Human autophagia is not motivated by suicidal intent, but may be related to the desire to seek pain.

There has been medical research into the relationship of prevalence of autophagia as a symptom of mental disorders including obsessive compulsive disorder, borderline personality disorder, anxiety, and Lesch-Nyhan Syndrome.

Medical research has displayed the presence of autophagia in rats. In a study conducted by Gopal, Female rats affected by spinal cord injuries displayed autophagia, by chewing their tails. Similarly, in a study conducted by Frost, patients affected by spinal cord injuries displayed extreme autophagia (i.e. finger and limb biting practices).

There is limited scientific research on Autophagia as the most common symptom of nail biting is prevalent in large parts of society. Hence, research into autophagia tends to be a part of broader questions of 'self injurious behaviour' (SIB), rather than being specifically about autophagia.

People who experience command hallucinations (often associated with schizophrenia and bipolar disorder) are most prone to self-mutilation, including the biting or eating one's own flesh. More examples of people who are very susceptible to severe self-mutilation like autophagia are ones with religious preoccupations, history of substance abuse, and intense social isolation.