Height potential is normally preserved if the duration and severity of illness are not significant or if the illness is accompanied by delayed bone age (especially prior to a bone age of approximately 15 years), as hypogonadism may partially counteract the effects of undernutrition on height by allowing for a longer duration of growth compared to controls. Appropriate early treatment can preserve height potential, and may even help to increase it in some post-anorexic subjects, due to factors such as long-term reduced estrogen-producing adipose tissue levels compared to premorbid levels. In some cases, especially where onset is before puberty, complications such as stunted growth and pubertal delay are usually reversible.Anorexia nervosa causes alterations in the female reproductive system; significant weight loss, as well as psychological stress and intense exercise, typically results in a cessation of menstruation in women who are past puberty. In patients with anorexia nervosa, there is a reduction of the secretion of gonadotropin releasing hormone in the central nervous system, preventing ovulation. Anorexia nervosa can also result in pubertal delay or arrest. Both height gain and pubertal development are dependent on the release of growth hormone and gonadotropins (LH and FSH) from the pituitary gland. Suppression of gonadotropins in people with anorexia nervosa has been documented. Typically, growth hormone (GH) levels are high, but levels of IGF-1, the downstream hormone that should be released in response to GH are low; this indicates a state of "resistance" to GH due to chronic starvation.
Theories to explain these lower rates of eating disorders, lower reporting and lower research rates in include the effects of westernisation, and culture change.Men (and women) who might otherwise be diagnosed with anorexia may not meet the DSM-IV criteria for BMI since they have muscle weight, but have very little fat. In many cases a subclinical "not otherwise specified" diagnosis is made instead; ED-NOS in the DSM-IV, and other specified feeding or eating disorder or unspecified feeding or eating disorder in the DSM-5. ED-NOS was the most diagnosed eating disorder in 2009, and it was also shown that AN did not differ significantly in eating pathology or general psychopathology from EDNOS involving restrictive eating.The elderly population is increasingly experiencing anorexia nervosa, which has been termed the "Anorexia of Aging". The eating disorder is similar to that of typical anorexia nervosa but is more often accompanied by the overuse of laxatives in order to purge the individual of ingested food. Most geriatric anorexia patients limit their food intake to dairy or grains, whereas an adolescent anorexic has a more general limitation.This eating disorder that affects older adults has two types - early onset and late onset. Early onset refers to a recurrence of anorexia in late life in an individual who experienced the disease during their youth. Late onset describes instances where the eating disorder begins for the first time late in life.