Many people with eating disorders do not meet the diagnostic criteria for anorexia nervosa, bulimia nervosa, or binge-eating disorder. These eating disorders have been given various names over the years (e.g. Eating Disorder Not Otherwise Specified, or more recently Other Specified Feeding or Eating Disorder). Here we use the less cumbersome term “other eating disorders”.
The category has recently attracted considerable attention as it has been discovered that it is far more common than previously assumed. In common with bulimia nervosa and anorexia nervosa, it mainly affects teenage girls and young women. Atypical eating disorders may be divided into five more-or-less distinct subgroups:
- Atypical anorexia nervosa. This is a subthreshold form of anorexia nervosa, in which despite significant weight loss the individual’s weight is above the specified threshold for anorexia nervosa.
- Bulimia nervosa (of low frequency and/or limited duration). This is a subthreshold form of bulimia nervosa in which the binge eating and extreme weight control behaviours occur less frequently than once a week and/or for a period of fewer than three months.
- Binge-eating disorder (of low frequency and/or limited duration). This is a subthreshold form of binge-eating disorder in which the binge eating occurs, on average, less frequently than once a week and/or for a period of fewer than three months.
- Purging disorder. This presents with recurrent purging (i.e. self-induced vomiting or the misuse of laxatives or diuretics) in the absence of binge-eating. However, since many people with purging disorder also have “subjective binges” (i.e. a binge in which the amount of eating is not unusually large given the circumstances) they may be better viewed as having a form of subthreshold bulimia nervosa.
- Night eating syndrome. This is a disorder characterised by recurrent episodes of eating in the evening or during the night. There is an awareness of the behaviour and it results in significant distress or impairment.