Compiled for Beat by Dr Ruth Cruickshank, Royal Holloway, University of London.
This summary looks at what research tells us about OSFED (other specified feeding or eating disorder). It highlights what we know, where there are gaps in research, and what future research could do to improve understanding, treatment, and support.
OSFED is diagnosed when someone has a clinically significant eating disorder, but their symptoms do not meet the full criteria for another specific diagnosis such as anorexia nervosa (AN), bulimia nervosa (BN), or binge eating disorder (BED). OSFED can involve restriction, binge eating, purging or other disordered eating behaviours. OSFED can look very different from person to person and does not mean their difficulties are less serious or that they need less support.
It is one of the most commonly diagnosed eating disorders and highlights that eating disorders do not always fit neatly into a single diagnostic category.
In the UK, there are two main systems used to classify and diagnose mental health conditions: the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), published by the American Psychiatric Association, and the International Classification of Diseases (ICD-11), published by the World Health Organization.
Beat uses ICD-11 as its reference framework when describing eating disorder diagnoses. However, much of the research into OSFED uses DSM-5, so it is important to understand how the two systems differ and why research may use different terms to describe experiences that are similar.
Both systems recognise that these presentations can cause significant distress, health risks, and difficulties in everyday life.
OSFED replaced the previous DSM-IV category of eating disorders not otherwise specified (EDNOS) in DSM-5 in 2013. At the same time, some conditions, including binge eating disorder (BED) and avoidant/restrictive food intake disorder (ARFID), became separate diagnoses in their own right.
DSM-5 describes five examples of how OSFED may present. They are specific to DSM-5 and are not considered separate OSFED diagnoses. OSFED is different for every person.
Atypical anorexia nervosa
when someone has all the symptoms of AN, but their weight does not meet the current diagnostic criteria for AN.
Bulimia nervosa of low frequency and/or limited duration when someone has binge/purge cycles less than once a week and/or for less than three months.
Binge eating disorder of low frequency and/or limited duration when someone experiences binge eating episodes, but these happen less than once a week and/or for less than three months.
Purging disorder when someone regularly gets rid of food they have eaten (for example by making themselves sick or misusing laxatives) in an attempt to affect their weight or shape, but this is not part of binge-purge cycles.
Night eating syndrome when someone repeatedly eats at night, either after waking up from sleep, or by eating a lot of food after their evening meal and this causes significant distress or affects their daily life.
The term 'atypical' is used within DSM-5 to describe presentations that do not meet certain diagnostic criteria, such as the weight criterion for AN. This does not mean that someone's eating disorder is less serious or less deserving of support.
ICD-11 also recognises OSFED as a diagnosis in its own right, but does not divide it into the same five examples used by DSM-5. Some presentations that were previously listed separately in ICD-10, including 'atypical' AN and 'atypical' BN, are now included within the broader OSFED category in ICD-11.
The ICD-11 states that:
“the presentation is characterized by abnormal eating or feeding behaviours. The symptoms do not fulfil the diagnostic requirements for any other disorder in the feeding and eating disorders grouping. The symptoms or behaviours result in significant risk or damage to health, significant distress, or significant impairment in personal, family, social, educational, occupational or other important areas of functioning (WHO, 2019).”
Although the two systems use different diagnostic criteria and terminology, both recognise that these eating disorder presentations can seriously affect someone's health and everyday life.
Eating disorder research largely continues to focus on AN, BN, and BED (Byrne & Fursland, 2024; Miskovic-Wheatley et al., 2023; Aouad et al., 2022) as well as on diagnostic criteria of body weight/BMI and behaviours (Dang et al., 2024).
Many studies comparing eating disorders do not include OSFED. When they do, they often treat it as one diagnosis rather than exploring the different ways it can present. This means there is much less research into the range of OSFED experiences, their impact on people's lives and the support that may be most helpful (Dang et al., 2024; Hagan & Christensen Pacella, 2024).
One possible reason for this lack of research is that OSFED covers such a wide range of experiences. This can make it harder for researchers to study and compare different presentations (Jenkins et al., 2021).
The language used in research may also affect how OSFED is understood and studied. Terms such as “subclinical” and “subthreshold” can create confusion about the difference between a diagnosed eating disorder and symptoms that do not meet diagnostic requirements. OSFED is a recognised diagnosis, not a term for symptoms that are automatically less serious or do not meet the threshold for support.
Some research also continues to use the previous classification EDNOS (eating disorder not otherwise specified). This is important to recognise when comparing findings across studies, as diagnostic categories and criteria have changed over time.
It’s important to note that both OSFED and EDNOS are not simply descriptions of disordered eating symptoms that fall below a clinical threshold. People with OSFED can experience significant distress, health problems, and difficulties with everyday life, and deserve appropriate treatment and support.
Research shows that OSFED can have a serious impact on people's physical and mental health, and on their everyday lives.
Studies have found that people with OSFED can experience difficulties and levels of distress that are just as serious as those experienced by people with other eating disorders (Wilkop et al., 2023; Withnell et al., 2022; Dang et al., 2024). In fact, some studies have found that people with OSFED experience higher levels of eating disorder symptoms and distress when compared to people with AN and BN (Booij et al., 2025).
For example, individuals with OSFED have been found to have higher weight gain and body-focused fears than other ED diagnoses (Butler et al., 2023), whilst another study found that distress is higher in presentations described as ‘atypical’ AN than in AN (Pruccoli et al., 2024). Lastly, an international study on the effects of Covid-19 lockdowns found that people with OSFED showed the most significant eating disorder symptoms and mental health difficulties compared to other eating disorder groups (Fernàndez-Aranda et al., 2021).
These findings show that OSFED should be taken just as seriously as other eating disorders and should not be considered a lower priority for treatment (Booij et al., 2025). Everyone with an eating disorder deserves to have their difficulties recognised and receive appropriate support.
It is thought that OSFED affects people right across the population (Mangweth-Matzek and Hoek 2017; Bryant et al., 2022), including people of different ages, genders, backgrounds, weights, and body types (Byrne & Fursland 2024).
There is currently limited reliable evidence showing how common OSFED is worldwide or in the UK. However, some studies suggest that it may account for a substantial proportion of eating disorder diagnoses. For example, one study found that around 47% of eating disorder diagnoses are OSFED, compared with 9% for AN, 18% for BN, and 9% for BED (Hay et al., 2017).
Some research also suggests that OSFED may be the eating disorder experienced by the highest proportion of people over their lifetime. One systematic review estimated that it affects about 7.4% of people, compared with 3.6% for AN, 2.1% for BN and 2% for BED (Galmiche et al., 2019). Similarly, a UK community study of midlife women found OSFED accounted for nearly 50% of cases of lifetime eating disorders (Micali et al., 2017). However, estimates can vary depending on the population studied and the diagnostic criteria used.
Recent research suggests that OSFED is the most common eating disorder diagnosis and that of the DSM-5 examples, presentations described as atypical AN, BN of low frequency or duration, and purging disorder are the most common (Attia & Guardia, 2024). Anorexia nervosa remains the most researched eating disorder, although research evidence remains limited (Brennan et al., 2023).
It is important to remember that many people with eating disorders never receive a formal diagnosis, meaning the true number of people affected by OSFED is likely to be much higher (Aouad et al., 2022).
There is limited evidence about which treatments work best for OSFED, and there is also little information about long-term recovery and outcomes (Hay et al., 2023).
Some research has found that cognitive behavioural therapy (CBT) and psychodynamic therapy have been linked with higher recovery rates for people with OSFED (Solmi et al., 2024). However, the range of experiences covered by the diagnosis means that one treatment approach may not be appropriate for all (Hay et al., 2023). As such, more research is needed to understand which treatments are most helpful for different presentations and individual needs.
Several barriers to diagnosis and treatment have been identified. These include:
(Pehlivan et al., 2022; Bryant et al., 2022; Todisco, 2018)
People may also be less likely to seek help for OSFED, such as seeing a GP, due to common misconceptions about eating disorders, like the stereotype that they only occur in thin young girls (Byrne & Fursland 2024). In addition, research has found that people with presentations described in DSM-5 as ‘atypical’ AN may be less likely to be referred for treatment or receive specialist care compared to those diagnosed with AN (Harrop et al., 2021). This highlights the importance of recognising eating disorder symptoms and risks regardless of someone's weight or diagnostic label.
It can be difficult to measure recovery and other outcomes for people with OSFED. This is partly because there is limited research and because the diagnosis covers such a wide range of experiences. Current research suggests that recovery and remission rates vary, with estimates ranging from around 23% to 50% (Fernández-Aranda et al., 2021; Miskovic-Wheatley et al., 2023).
Research suggests that individuals with OSFED are less likely to recover the longer their illness lasts (Fernàndez Arnanda et al., 2021), highlighting the importance of early diagnosis and treatment. Moreover, people can move between different eating disorder diagnoses over time (Miskovic-Wheatley et al., 2023). For example, people diagnosed with AN, BN or BED may later receive an OSFED diagnosis in 16-19% of cases (Solmi et al., 2024). This does not necessarily mean that their eating disorder has become more or less severe; it may reflect changes in their symptoms over time or how those symptoms meet diagnostic criteria.
For those with OSFED, one review reported three possible outcomes:
(Solmi et al., 2024).
Research into the global impact of eating disorders has historically focused on a limited number of diagnoses. The original Global Burden of Disease estimates included anorexia nervosa and bulimia nervosa but did not fully account for the impact of binge eating disorder and OSFED.
This means that the global impact of eating disorders has probably been underestimated, and the true number of people affected is likely to be much higher, with a potential 24.6 million individuals with OSFED unrepresented (Santomauro et al., 2019).
This matters because if the experiences of people with OSFED are not adequately represented in research, their needs may also be overlooked when decisions are made about eating disorder care and support.
UFED was classified in the DSM-5 in 2013 and can be used when clinicians identify disordered eating causing significant distress and affecting someone’s ability to function in important areas of life, but their symptoms do not meet the criteria for any of the recognised eating disorder diagnoses (including OSFED). It may also be used when the clinician does not specify the reason, or when there is not enough information available to make a more specific diagnosis. It is a separate diagnostic category to OSFED.
ICD-11 also distinguishes between other specified and unspecified feeding or eating disorders (FEDU). Its unspecified category may be used when there is insufficient information to make a more specific diagnosis.
UFED and FEDU have been researched even less than OSFED, but evidence suggests that they are just as serious as other eating disorders (Schoen et al., 2019). Some researchers have suggested that OSFED and UFED together account for around half of all eating disorder diagnoses (Krug et al., 2022), which highlights how much remains unknown about these eating disorders and further confirms the need for more research into different experiences, as a significant proportion of eating disorder presentations are poorly understood (Aouad et al., 2022).
OSFED may be one of the most common eating disorder diagnoses, yet it remains under-represented in research. There is an urgent need for more research to inform understanding, resourcing, treatment, and prevention.
Research is also required to better understand how common OSFED is, including among under-researched groups, and to develop early identification tools for research and clinical use. These tools should help researchers and clinicians better understand the different ways OSFED can present (Withnell et al., 2022) and appropriate evidence-based treatments (Byrne & Fursland, 2024).
Recent reviews of research on OSFED highlighted the need to address this lack of research and improve the ways it is studied. Researchers suggest that current methods may not fully capture the range of experiences within OSFED. They also raised questions about whether the diagnostic criteria for other eating disorders should be broadened, and whether criteria for OSFED diagnoses should be refined.
Overall, these researchers argue for a shift in how eating disorders are understood and diagnosed. Instead of focusing mainly on BMI and observable behaviours, they suggest placing greater emphasis on people’s lived experiences, including the emotional impact and the ways eating disorders affect daily life across different identities, cultures and social contexts (Dang et al., 2024; Claudino & Hay, 2024; Hagan & Christensen Pacella, 2024; Keel, 2024).
Other areas identified for future research include:
More research is needed to ensure that people with OSFED are not overlooked, and that eating disorder diagnosis, treatment and support reflect the full range of people's experiences.
We asked someone with lived experience what this research means to them. Read what they said below.
"Better understanding of eating disorders is necessary within both the medical field and public understanding to prevent people with these conditions from feeling isolated. Similarly, a refocus on the lived experience of those who suffer with these conditions rather than unhelpful metrics such as BMI will do a lot to help folks feel like they cannot be simply dismissed on the basis of measurements that fail to capture the experience of those living it."
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