Diagnosing Anorexia Nervosa VS EDNOS: What Does the Weight Criteria Really Mean?


Making a distinction between EDNOS and Anorexia Nervosa is a tricky one when it comes down to the Atypical Anorexia Nervosa (a type of EDNOS) side of things. There are those that adhere to the strict weight criteria for the diagnosis of Anorexia Nervosa (even though there is now no specific cut off point in the DSM-V), and there are those that use it as a guideline. The argument on whether or not a specfic weight is required or not for the diagnosis of Anorexia Nervosa is rife across the eating disorder communities, so I decided to do some research on what the medical community has to say on the matter.

According to the DSM-5 criteria, to be diagnosed as having Anorexia Nervosa a person should display:

  • Persistent restriction of energy intake leading to significantly low body weight (in context of what is minimally expected for age, sex, developmental trajectory, and physical health) .
  • Either an intense fear of gaining weight or of becoming fat, or persistent behaviour that interferes with weight gain (even though significantly low weight).
  • Disturbance in the way one’s body weight or shape is experienced, undue influence of body shape and weight on self-evaluation, or persistent lack of recognition of the seriousness of the current low body weight.

The Subtypes of Anorexia Nervosa are: restricting type, and binge-eating/purging type.

(I should also first mention that the DSM-V has already been widely criticised, and The National Institute of Mental Health withdrew their support for the manual, stating that “patients with mental disorders deserve better.”  Another thing to consider is that the cut off point for what is a healthy BMI varies from medical institution to medical institution. Many use 18.5 as the cut off point. Others use 19. My pharmacist had a chart on the wall that stated that a normal BMI was between 20 and 25 (it also states that here). So that already can create problems when there is no consensus between medical communities on what is underweight. You can go to one doctor’s surgery and be told you are underweight and another where you are told you are not. Really, we should just be going on each personal individually, and using these charts as a guide.)

To start with, Kate Donovan wrote “Problems in the way we diagnose anorexia” – a blog post exploring the weight criteria when we still had the DSM-IV – which is relevant because Anorexia Nervosa is still being diagnosed using an outdated weight criteria.

The reason this is so important is that Atypical Anorexia Nervosa and Anorexia Nervosa are barely distinguishable – so why are there two different diagnosis’s dividing the two when they are the same disease and both require extremely similar treatment which only differs in terms of the individual rather than the label? Results of Jennifer Thomas’s study (The relationship between EDNOS and officially recognized eating disorders: meta-analysis and implications for DSM) indicated that EDNOS did not differ significantly from AN on eating pathology or general psychopathology, and “moderator analyses indicated that EDNOS groups who met all diagnostic criteria for AN except for amenorrhea did not differ significantly from full syndrome cases.” (Jennifer Thomas is an assistant Professor of Psychology at Harvard.)

In another of her studies (which is about the criteria in the DSM-IV “refusal to maintain body weight at or above a minimally normal weight for age and height e.g. weight loss leading to maintenance of body weight less than 85% of that expected”), she writes

“Although the 85% weight cut-off is intended to represent a ‘suggested guideline’ for diagnosis (APA, 2000, p. 584), investigators who enroll eating disorder patients in clinical trials (Dare et al. 2001; Powers et al. 2002) and insurance companies that determine treatment eligibility typically adhere to this percentage when assessing underweight. The 85% criterion is also frequently used to calculate AN prevalence in epidemiological studies (Walters & Kendler, 1995; Garfinkelet al. 1996), which inform the perceived public health significance of the disorder. The widespread use of the 85% criterion probably reflects a desire to standardize diagnosis across diverse settings.”

She also states;

“Data from clinical and non-clinical samples suggest that eating disorder not otherwise specified (EDNOS) is the most prevalent of DSM-IV eating disorders, and individuals who meet all criteria for AN except the weight cut-off represent a common subtype of this group (Watson & Andersen, 2003; McIntosh et al. 2004). A computer simulation of 193 eating-disorder treatment seekers indicated that the prevalence of AN would increase significantly if the weight criterion were relaxed from 85% to 90% of EBW (Thaw et al. 2001). It is therefore likely that if some clinics use more lenient methods of calculating EBW, they will diagnose a greater proportion of their patients with AN and a relatively smaller proportion of patients with EDNOS, even if they consistently apply an 85% cut-off.”

Jennifer Thomas also makes an important point regarding diagnosis and treatment regarding weight cut off points:

“The finding that investigators use different weight criteria for AN has important implications for eating disorder diagnosis, treatment, research and insurance reimbursement. Our results raise the possibility that a patient of a particular height, weight and symptom profile could receive a diagnosis of AN at one treatment center and a diagnosis of BN or EDNOS at another, and be eligible for one investigator’s AN treatment outcome study but not another. On average, discrepancies are possible within a 15-lb weight range for females and a 25-lb weight range for males, and could occur even if the assessing clinicians at each treatment center referred to the same DSM-IV criteria to assign diagnoses. If each clinician then attempted to recommend an evidence-based treatment, the patient diagnosed by the stricter weight cut-off and therefore classified as BN or EDNOS might receive out-patient therapy whereas the patient diagnosed by the more lenient weight cut-off and therefore classified as AN might receive a more intensive intervention (e.g. in-patient care) because of the perception that he or she is more underweight.”

She also made the following comment on a post by Science of Eating Disorders (‘Are There Any Meaningful Differences Between Subthreshold and Full Syndrome Anorexia Nervosa?’):

“I share your frustration with the 85% EBW guideline — it’s not only arbitrary but inconsistently applied (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2847836/). Interestingly, the DSM-IV Work Group never meant it to be a “cut-off” (just a guideline), so it’s a good thing it’s being omitted from DSM-5. My work also suggests that EDNOS is typically just as severe as AN and BN (http://www.ncbi.nlm.nih.gov/pubmed/19379023), and clinically I think too many patients find their suffering invalidated when they are diagnosed not with a specific eating disorder, but an acronym. I also agree with you that DSM-5 represents a big improvement (especially the inclusion of named subtypes like purging disorder)…”

The post by Science of Eating Disorders (which is linked above) talks about a study conducted by Daniel Le Grange and colleagues, published in the European Eating Disorders Review, where they compared eating-related and psychopathology measures between 59 anorexia nervosa and 59 subthreshold anorexia nervosa women, and found that there were no differences between the two other than the bingeing and purging frequency, which was higher in the AN group, and body checking behaviours, which was higher in the EDNOS-AN group. They said:

“There is little evidence that participants with EDNOS-AN were any different from those with AN. Therefore, our results confirm the now accepted notion that menstrual status is probably not a helpful diagnostic marker for AN (Attia, Robero, & Steinglass, 2008) and also challenge the generally accepted cut point of 85% of ideal body weight (or BMI 17.5 ) for a diagnosis of AN.”

We know that the weight threshold that is used so rigidly by some can cause massive problems for those seeking treatment: many insurance companies and inpatient facilities will only accept those meeting the “anorexic BMI” criteria – even though the specific weight criteria has been removed with the publication of the DSM-V. We also know that the DSM-V is to be used as a guide, and that the “anorexic BMI” is also a guide, not an absolute. There is no weight that you MUST be to be diagnosed with anorexia nervosa.

What I’ve seen from observing both the reactions from some who have suffered from eating disorders (specifically those who have, or are in recovery from, anorexia nervosa) and doctors in response to the idea that you don’t have to meet the weight criteria (that actually doesn’t exist any more in the DSM-V) of 17.5 to be diagnosed with anorexia nervosa, it is those with anorexia that tend to become outraged when it is suggested, whereas all different doctors have different opinions, many leaning towards using the manual as a guideline. Medical professionals that I have spoken to recently do not believe in weight criteria rigidity being exceedingly important to the diagnosis of Anorexia Nervosa. I recently spoke to a doctor in the UK, and a medical director in the US. Both told me that the DSM-V (and the ICD-10) are guidelines, and are to be used as such. When asked about anorexia, EDNOS, and the weight criteria, the US medical director said it is subjective:

“DSM criteria are not absolute, like many things in medicine with variable presentations, symptoms, and severities. The diagnostic criteria are best used as a guide. Unfortunately some take it too literally (many payors, insurances, etc) will not cover care unless strictly adherent to these criteria. I believe the key is to recognize and anticipate before the process progresses to a unstable or potential irreversible condition…Following strict criteria in my opinion results in delayed therapy of patients in worse conditions.”

In the DSM-V, it states:

“Criterion A requires that the individual’s weight be significantly low (i.e., less than minimally normal or, for children and adolescents, less than that minimally expected).Weight assessment can be challenging because normal weight range differs among individuals, and different thresholds have been published defining thinness or underweight status. Body mass index (BMI; calculated as weight in kilograms/height in meters2) is a useful measure to assess body weight for height. For adults, a BMI of 18.5 kg/m2 has been employed by the Centers for Disease Control and Prevention (CDC) (Centers for Disease Control and Prevention 2011) and the World Health Organization (WHO) (World Health Organization 1995) as the lower limit of normal body weight. Therefore, most adults with a BMI greater than or equal to 18.5 kg/m2 would not be considered to have a significantly low body weight. On the other hand, a BMI of lower than 17.0 kg/m2 has been considered by the WHO to indicate moderate or severe thinness (World Health Organization 1995); therefore, an individual with a BMI less than 17.0 kg/m2 would likely be considered to have a significantly low weight. An adult with a BMI between 17.0 and 18.5 kg/m2, or even above 18.5 kg/m2, might be considered to have a significantly low weight if clinical history or other physiological information supports this judgment. For children and adolescents, determining a BMI-for-age percentile is useful (see, e.g., the CDC BMI percentile calculator for children and teenagers). As for adults, it is not possible to provide definitive standards for judging whether a child’s or an adolescent’s weight is significantly low, and variations in developmental trajectories among youth limit the utility of simple numerical guidelines. The CDC has used a BMI-for-age below the 5th percentile as suggesting  underweight; however, children and adolescents with a BMI above this benchmark may be judged to be significantly underweight in light of failure to maintain their expected growth trajectory. In summary, in determining whether Criterion A is met, the clinician should consider available numerical guidelines, as well as the individual’s body build, weight history, and any physiological disturbances.”

This means that people need to be treated on an individual basis, and not strictly by a weight criteria.

What I find worrying is that some (emphasis on some) of those with the diagnosis of Anorexia Nervosa feel that the criteria should be rigid: so much so that they actually believe that it is. I would suggest that this is because some can see it as a badge of honour that you only “deserve” when you reach a certain weight. Those with such black and white thinking regarding AN are particularly (and disorderedly) protective of the diagnosis. This only reinforces to those diagnosed with EDNOS that they are “not sick enough” until they have “achieved” that particular BMI. It also reinforces the (untrue) notion that you can only be diagnosed with AN at a certain weight, and this results in the spreading of misinformation.  It is important that we are educated about the facts, rather than going purely on beliefs when we are not medical professionals ourselves. The negative emotional connection some of those with Anorexia Nervosa seem to have to the diagnosis and the “badge of honour” mentality can cloud judgement and rational thought, and become an issue as it invalidates others.

Obviously in no way is this article intended to invalidate those with EDNOS. In fact, I hope to validate the diagnosis more as those with EDNOS routinely present with symptoms and behaviours that are as serious as AN or BN. My aim was to show that there is barely any difference between those with Atypical Anorexia Nervosa and those with Anorexia Nervosa, and it is my opinion that they should all be diagnosed with the same illness, and any difference in physical symptoms be treated accordingly. Any doctor or professional who is worth their salt will pay attention to the mental and physical condition their patient is in and diagnose that way, or if they have been diagnosed before, they will reassess and treat accordingly. Using the guidelines as absolutes can be extremely harmful, misguided, and unhelpful, and spreading the notion that they are absolutes within the eating disorder community on social media and within our culture in general, is harmful to those seeking help, support, and treatment.


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