Psych · general-adult
Other specified feeding or eating disorders (OSFED)
Also known as OSFED · EDNOS · Atypical anorexia nervosa · Purging disorder · Night eating syndrome · UFED · Subthreshold bulimia · Other specified feeding or eating disorder
Exam-exhaustive fellowship reference on OSFED — DSM-5-TR named examples (atypical AN, BN/BED of low frequency/limited duration, purging disorder, night eating syndrome), UFED distinction, medical risk despite non-low BMI, CBT-E/transdiagnostic care, RANZCP/NICE/APA framing. FRANZCP-primary, globally tagged.
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Target exams
Red flags
- Atypical anorexia nervosa with rapid or large weight loss, bradycardia, hypotension, hypothermia, or orthostasis — medical instability can match full AN despite normal or high BMI
- Purging with hypokalaemia, ECG change, syncope, or volume depletion — medical stabilisation before pure outpatient psychiatry
- Active suicidal ideation or recent attempt — residual diagnostic label does not lower suicide risk
- Dismissing clinically significant restriction, purging, or bingeing as 'not sick enough' because full AN/BN/BED criteria are incomplete
- Refeeding risk after prolonged restriction in atypical AN — monitor phosphate, potassium, magnesium even when weight is not low
- Pregnancy with active purging or severe restriction — urgent obstetric–psychiatric coordination
Meet the patient
A 19-year-old dance student is referred because her periods have stopped. Her BMI reads 23 — "reassuring," the GP wrote in the referral letter. She has lost 18 kg in five months. Her heart rate is 42, her standing blood pressure drops to 88 over 52, and her phosphate sits low at 0.55 mmol per litre. She runs 10 km a day and is terrified of regain.[3][4]
She does not meet anorexia nervosa — her weight is not "significantly low." She meets atypical anorexia nervosa, and she is medically unstable on a normal BMI. Two questions the examiner will fire at you: "Is she safe for outpatient psychiatry?" and "What makes this OSFED and not AN — and why is the distinction a trap?" This whole topic is the answer to both.[3][16]
References16ShowHide
- [1]Hay P, Chinn D, Forbes D, Madden S, et al. Royal Australian and New Zealand College of Psychiatrists clinical practice guidelines for the treatment of eating disorders Aust N Z J Psychiatry, 2014.PMID 25351912
- [2]Treasure J, Duarte TA, Schmidt U Eating disorders Lancet, 2020.PMID 32171414
- [3]Sawyer SM, Whitelaw M, Le Grange D, Yeo M, Hughes EK Physical and Psychological Morbidity in Adolescents With Atypical Anorexia Nervosa Pediatrics, 2016.PMID 27025958
- [4]Whitelaw M, Lee KJ, Gilbertson H, Sawyer SM Predictors of Complications in Anorexia Nervosa and Atypical Anorexia Nervosa: Degree of Underweight or Extent and Recency of Weight Loss? J Adolesc Health, 2018.PMID 30454732
- [5]Keel PK, Wolfe BE, Liddle RA, De Young KP, Jimerson DC Clinical features and physiological response to a test meal in purging disorder and bulimia nervosa Arch Gen Psychiatry, 2007.PMID 17768271
- [6]Keel PK Purging disorder: recent advances and future challenges Curr Opin Psychiatry, 2019.PMID 31306252
- [7]Allison KC, Lundgren JD, O'Reardon JP, Geliebter A, et al. Proposed diagnostic criteria for night eating syndrome Int J Eat Disord, 2010.PMID 19378289
- [8]Fairburn CG, Cooper Z, Doll HA, O'Connor ME, et al. Transdiagnostic cognitive-behavioral therapy for patients with eating disorders: a two-site trial with 60-week follow-up Am J Psychiatry, 2009.PMID 19074978
- [9]Thomas JJ, Vartanian LR, Brownell KD The relationship between eating disorder not otherwise specified (EDNOS) and officially recognized eating disorders: meta-analysis and implications for DSM Psychol Bull, 2009.PMID 19379023
- [10]Mitchison D, Mond J, Bussey K, Griffiths S, et al. DSM-5 full syndrome, other specified, and unspecified eating disorders in Australian adolescents: prevalence and clinical significance Psychol Med, 2020.PMID 31043181
- [11]Mustelin L, Lehtokari VL, Keski-Rahkonen A Other specified and unspecified feeding or eating disorders among women in the community Int J Eat Disord, 2016.PMID 27442991
- [12]Arcelus J, Mitchell AJ, Wales J, Nielsen S Mortality rates in patients with anorexia nervosa and other eating disorders. A meta-analysis of 36 studies Arch Gen Psychiatry, 2011.PMID 21727255
- [13]Crow SJ, Peterson CB, Swanson SA, Raymond NC, et al. Increased mortality in bulimia nervosa and other eating disorders Am J Psychiatry, 2009.PMID 19833789
- [14]Forney KJ, Buchman-Schmitt JM, Keel PK, Frank GK The medical complications associated with purging Int J Eat Disord, 2016.PMID 26876429
- [15]Eddy KT, Dorer DJ, Franko DL, Tahilani K, et al. Diagnostic crossover in anorexia nervosa and bulimia nervosa: implications for DSM-V Am J Psychiatry, 2008.PMID 18198267
- [16]Golden NH, Katzman DK, Sawyer SM, et al. Position Paper of the Society for Adolescent Health and Medicine: medical management of restrictive eating disorders in adolescents and young adults J Adolesc Health, 2015.PMID 25530605