Eating Disorder not Otherwise Specified is most commonly referred to as 'EDNOS'. 

EDNOS is currently recognised by the DSM-IV as a "category [of] disorders of eating that do not meet the criteria for any specific eating disorder"

This diagnosis is usually given to sufferers who very obviously have disordered eating, but do not fit all of the categories for a specific diagnosis, i.e. anorexia nervosa. EDNOS covers a wide spectrum of eating behaviours, ranging from eating behaviours that are obviously disordered but are not sufficiently serious enough to warrant a diagnosis of anorexia or bulimia – an example given by the DSM is yo-yo dieting. On the other hand, it also characterises a lot more serious cases of disordered eating, for example an individual with anorexia who may still menstruate. Individuals with EDNOS can be just at risk of serious health complications (as associated with anorexia and bulimia), and should therefore be treated appropriately, and not ‘brushed under the rug’ as can be the case. Binge-eating disorder also at the moment comes under the heading of ‘EDNOS’.

Sadly, there is a lot of stigma attached, because to both sufferer’s and sadly to some professionals, it gives the illusion that the sufferer is “not that ill”, when in fact this is not the case at all, and those with EDNOS need just as much treatment as someone who may have a full diagnosis of anorexia or bulimia.
This is not the case, just with all other eating disorders, EDNOS can be just as serious and life-threatening as any other disorders. 

"Having a disorder with the words "not otherwise specified" directly in the name can be frustrating, because it's often not taken as seriously. Most of my friends and my boyfriend at the time had never heard of EDNOS. They knew that I had lost weight, spent a lot of time exercising and had poor eating habits, but I used excuses to explain why, and since my weight never dropped to a "dangerous level", my excuses worked. When I finally chose to open up about my disordered eating to a psychiatrist, she knew to diagnose me with an eating disorder, but made very little attempt to council me, instead telling me that I simply had to eat, as this would help to improve the depression that I also suffered from. Because disordered eating occurs on a spectrum, a lot of days I find myself wandering down the same path all over again, and honestly, it's much too easy to find yourself relying on old habits, because you know how to live that way. But I also know what's waiting for me at the end of that path, and so I make a daily conscious effort to choose healthy - to choose happy.  Whether you are recovered, still struggling, going through treatment, or just notice one or two small disordered eating patterns that you follow, there's no right or wrong time to get help. If people don't understand your disorder, or don't believe that it's real, don't be afraid to educate them on the reality and consequences of EDNOS."