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.
Diagnosis can be challenging, risk assessment may not be performed accurately, consent and the need for compulsion may not be assessed appropriately, refeeding syndrome may be missed or poorly treated and the behavioural and family problems in AN may be missed or poorly managed. Guidelines published by the Royal College of Psychiatrists recommend that medical and psychiatric experts work together in managing severely ill people with AN. Refeeding syndrome
The rate of refeeding can be difficult to establish, because the fear of refeeding syndrome (RFS) can lead to underfeeding. It is thought that RFS, with falling phosphate and potassium levels,  is more likely to occur when BMI is very low, and when medical comorbidities such as infection or cardiac failure, are present. In those circumstances, it is recommended to start refeeding slowly but to build up rapidly as long as RFS does not occur. Recommendations on energy requirements vary, from 5–10 kcal/kg/day in the most medically compromised patients, who appear to have the highest risk of RFS, to 1900 kcal/day. Experience of treatment
Patients involved in treatment sometimes felt that treatment focused on biological aspects of body weight and eating behaviour change rather than their perceptions or emotional state. : 8  Patients felt that a therapists trust in them shown by being treated as a complete person with their own capacities was significant. : 9  Some patients defined recovery from AN in terms of reclaiming a lost identity.