Blood Parameters in Children and Adolescents With Underweight and Atypical Anorexia Nervosa.

OBJECTIVE: This study aimed to identify biochemical, hematological, and endocrinological abnormalities in a sample of children and adolescents with underweight AN and atypical AN and to compare these results between the two groups. METHOD: Based on the 5th BMI-percentile admission, adolescents with underweight AN (n = 520) and atypical AN (n = 255) were included and medical records were reviewed. RESULTS: Low prealbumin (35%) and neutropenia (39%), and several abnormalities in endocrinological parameters (50%) were the most common alterations found in the whole sample. Compared to the atypical AN group, the underweight AN group had significantly higher frequencies of elevated cholesterol (OR = 2.50; p < 0.001) and alanine aminotransferase (OR = 0.22; p = 0.005) and of reduced insulin-like growth (IGF) factor-1 (OR = 0.29; p < 0.001), T3 (OR = 0.46; p < 0.001), luteinizing hormone (OR = 0.24; p < 0.001), follicle stimulating hormone (OR = 0.58; p = 0.004), and 17b-estradiol (OR = 0.39; p < 0.001). However, other blood parameters showed similar alterations in both groups. DISCUSSION: Both groups showed abnormalities in the same blood parameters, but some abnormal parameters were more common in the underweight AN group. These results suggest that atypical AN and underweight AN could present similar risks of certain medical complications.

Psychopathological and Organic Features of Atypical Anorexia Nervosa in Developmental Age: A Systematic Review.

PURPOSE: This study aimed to comprehensively report the epidemiological and clinical features of atypical anorexia nervosa (AAN) in children and adolescents. METHODS: In May 2024, a systematic review was performed using Medline, Cochrane Library, ClinicalTrials.gov, and relevant websites. Following PRISMA guidelines, 234 articles were screened for studies on DSM-5-defined AAN. A standardized checklist-the JBI critical appraisal tool-was adopted in assessing methodology, and 13 retained studies passed the screening and critical appraisal process for the final review. The Newcastle-Ottawa Scale was utilized to assess the risk of bias in cohort and case-control studies, ensuring a comprehensive evaluation of methodological quality. RESULTS: AAN prevalence in young age groups is 2.8%, with a cumulative 2.8% incidence over 8 years. Incidence is 366 per 100,000 person-years, and the average episode duration is 11.6 months, with a 71% remission rate. Diagnostic persistence for AAN is less stable than other restrictive feeding and eating disorders (FEDs). AAN individuals exhibit higher EDE-Q scores, more severe distress, and distinct BMI differences compared to those with anorexia nervosa and controls. The diagnostic transition from the DSM-IV to the DSM-5 shows that AAN patients are predominantly female, slightly older, and with higher weight. CONCLUSIONS: This study yields concrete insights into the features of AAN in the developmental age, highlighting demographic variations, clinical presentations, and treatment outcomes. Recognizing the unique challenges faced by AAN individuals is vital for tailoring effective interventions and improving overall care within the FED spectrum.

Atypical anorexia nervosa: A scoping review to determine priorities in research and clinical practice.

BACKGROUND: There is currently a limited understanding of the identification, nature, and treatment of Atypical Anorexia Nervosa (AAN). Recent systematic reviews have identified only small numbers of candidate papers, and some areas lack any meaningful review so far - particularly treatment outcomes. A key issue is the lack of clarity in the literature regarding the definition of weight loss criteria. OBJECTIVES: This scoping review aimed to determine the nature and extent of our knowledge of AAN, in order to assist in the development of future systematic reviews and meta-analyses, as well as indicating what further research is needed. METHOD: Following the identification of 6747 records, 317 records using the term AAN or a defined equivalent were identified from six databases, including the 'grey' literature. RESULTS: Of the 317 studies, 111 provided participant characteristics, and only 10 provided discrete treatment outcomes. Each of these subsets of the data are tabulated and supported with supplementary material, so that future systematic reviewers can access this resource. DISCUSSION: The pattern and content of the existing studies allows recommendations to be made regarding future reviews, research and clinical practice. There is a particular need for clear weight/weight loss criteria and adequate interventions.

Weight gain and eating disorder symptoms among individuals with atypical anorexia nervosa.

OBJECTIVE: The purpose of this study was to examine the association between weight gain and eating disorder (ED) symptoms among adults receiving treatment for atypical anorexia nervosa (AAN), to determine whether those who had a higher percent of expected body weight (%EBW) at discharge exhibited lower ED symptoms than those who gained less weight, and to compare this group to a matched sample of patients with anorexia nervosa (AN). METHOD: Participants were 96 adults receiving treatment at an ED treatment facility between December 2020 and May 2023. The Eating Disorder Examination-Questionnaire (EDE-Q) was completed at admission and discharge, and %EBW was obtained at admission and discharge. RESULTS: All EDE-Q subscale scores improved from admission to discharge for patients with AAN and patients with AN. Neither %EBW at discharge nor weight gain were associated with EDE-Q subscale scores for those with AAN. For patients with AN, %EBW at discharge and weight gain were associated with EDE-Q Restraint at discharge. CONCLUSIONS: Weight restoring to a higher level and gaining more weight were not associated with EDE-Q scores at discharge for AAN. Further research is needed to determine how weight restoration using intensive treatment settings affects remission and recovery in patients with AAN.

Comparing changes in eating disorder psychopathology and comorbid symptoms over treatment in anorexia nervosa and atypical anorexia nervosa in a partial hospitalization program.

OBJECTIVE: The objective of this study is to compare treatment trajectories in anorexia nervosa (AN) and atypical AN. METHOD: Adolescents and adults with AN (n = 319) or atypical AN (n = 67) in a partial hospitalization program (PHP) completed diagnostic interviews and self-report questionnaires measuring eating disorder (ED), depression, and anxiety symptoms throughout treatment. RESULTS: Premorbid weight loss did not differ between diagnoses. Individuals with atypical AN had more comorbid diagnoses, but groups did not differ on specific diagnoses. ED psychopathology and comorbid symptoms of depression/anxiety did not differ at admission between groups nor did rate of change in ED psychopathology and comorbid symptoms of depression/anxiety from admission to 1-month. From admission to discharge, individuals with atypical AN had a faster reduction in ED psychopathology and comorbid symptoms of depression and anxiety (ps < 0.05; rs = 0.01-0.32); however, there were no group differences in ED psychopathology or depression symptoms at discharge (ps>.50; ds = .01-.30). Individuals with atypical AN had lower anxiety at discharge compared to individuals with AN (p = 0.05; d = .4). Length of stay did not differ between groups (p = 0.11; d = .21). DISCUSSION: Groups had similar ED treatment trajectories, suggesting more similarities than differences. PHP may also be effective for AAN. PUBLIC SIGNIFICANCE: This study supports previous research that individuals with AN and atypical AN have more similarities than differences. Results from this study indicate that individuals with AN and atypical AN have similar treatment outcomes for both ED psychopathology and depressive symptoms; however, individuals with atypical AN have lower anxiety symptoms at discharge compared to individuals with AN. AN and atypical AN also have more symptom similarity at admission and throughout treatment, which challenges their current designation as distinct disorders.

Nutritional Assessment of Children and Adolescents with Atypical Anorexia Nervosa: A Preliminary Longitudinal Investigation Using the 24-h Dietary Recall.

BACKGROUND: Atypical Anorexia Nervosa (AAN) is a Feeding and Eating Disorder characterized by fear of gaining weight and body image disturbance, in the absence of significantly low body weight. AAN may present specific clinical and psychopathological features. Nonetheless, the literature lacks data concerning the nutritional characteristics and body composition of children and adolescents with AAN and their variation over time. METHODS: Case series, including 17 children and adolescents with AAN. All the patients were assessed at the first evaluation (T0) with a standardized dietary assessment (24 h Dietary Recall, 24 hDR). Nutritional data were compared with European dietary reference values (DRVs). Body composition parameters (weight, fat mass, fat-free mass) and their changes over time at two (T1) and six (T2) months were collected as well, using a Bioelectrical impedance analysis (Wunder WBA300 with four poles and foot contact; impedance frequency 50 kHz 500 µA; impedance measurement range 200~1000 Ω/0.1 Ω). RESULTS: The included individuals presented eating behaviors oriented towards significantly low daily energy intake (p < 0.001) compared with DRVs set by the European Food Safety Authority (EFSA) (with low carbohydrates and fats), and increased proteins (p < 0.001). A longer latency before observation (illness duration before observation) correlated with a negative change in weight. Body composition parameters were described, with no significant changes across the six-month outpatient assessment. DISCUSSION: This is the first research to systematically assess the body composition and nutritional features of a group of individuals with AAN in the developmental age. Further research should assess the effect of targeted treatment interventions on body composition and nutritional features.

Differentiating anorexia nervosa and atypical anorexia nervosa with absolute weight cut-offs results in a skewed distribution for premorbid weight among youth.

OBJECTIVE: Anorexia nervosa (AN) and atypical AN are conceptualized as distinct illnesses, despite similar characteristics and sequelae. Whereas DSM-5 differentiates youth with AN and atypical AN by the presence of clinical 'underweight' (i.e., 5th BMI percentile for age-and-sex (BMI%)), we hypothesized that using this weight cut-off to discern diagnoses creates a skewed distribution for premorbid weight. METHOD: Participants included hospitalized youth with AN (n = 165, 43.1%) and atypical AN (n = 218, 56.9%). Frequency analyses and chi-square tests assessed the distribution of premorbid BMI z-scores (BMIz) for diagnosis. Non-parametric Spearman correlations and Stepwise Linear regressions examined relationships between premorbid BMIz, admission BMIz, and weight loss in kg. RESULTS: Premorbid BMIz distributions differed significantly for diagnosis (p < .001), with an underrepresentation of 'overweight/obesity' (i.e., BMI% ≥ 85th) in AN. Despite commensurate weight loss in AN and atypical AN, patients with premorbid 'overweight/obesity' were 8.31 times more likely to have atypical AN than patients with premorbid BMI% < 85th. Premorbid BMIz explained 57% and 39% of the variance in admission BMIz and weight loss, respectively. DISCUSSION: Findings support a homogenous model of AN and atypical AN, with weight loss predicted by premorbid BMI in both illnesses. Accordingly, premorbid BMI and weight loss (versus presenting BMI) may better denote the presence of an AN-like phenotype across the weight spectrum. Findings also suggest that differentiating diagnoses with BMI% < 5th requires that youth with higher BMIs lose disproportionately more weight for an AN diagnosis. This is problematic given unique treatment barriers experienced in atypical AN. PUBLIC SIGNIFICANCE: Anorexia nervosa (AN) and atypical AN are considered distinct conditions in youth, with differential diagnosis hinging upon a presenting weight status of 'underweight' (i.e., BMI percentile for age-and-sex (BMI%) < 5th). In our study, youth with premorbid 'overweight/obesity' (BMI% ≥ 85th) disproportionately remained above this threshold, despite similar weight loss. Coupled with prior evidence for commensurate characteristics and sequelae in both diagnoses, we propose that DSM-5 differentiation of AN and atypical AN inadvertently reinforces weight stigma and may contribute to treatment disparities in atypical AN.

Clinical effectiveness, cost-effectiveness and process evaluation of group schema therapy for eating disorders: study protocol for a multicenter randomized controlled trial.

BACKGROUND: Eating disorders (EDs), such as (atypical) Anorexia (AN) and Bulimia Nervosa (BN), are difficult to treat, causing socioeconomic impediments. Although enhanced cognitive behavioral therapy (CBT-E) is widely considered clinically effective, it may not be the most beneficial treatment for (atypical) AN and BN patients who do not show a rapid response after the first 4 weeks (8 sessions) of a CBT-E treatment. Alternatively, group schema therapy (GST) may be a valuable treatment for this ED population. Even though GST for EDs has yielded promising preliminary findings, the current body of evidence requires expansion. On top of that, data on cost-effectiveness is lacking. In light of these gaps, we aim to describe a protocol to examine whether GST is more (1) clinically effective and (2) cost-effective than CBT-E for (atypical) AN and BN patients, who do not show a rapid response after the first 4 weeks of treatment. Additionally, we will conduct (3) process evaluations for both treatments. METHODS: Using a multicenter RCT design, 232 Dutch (atypical) AN and BN patients with a CBT-E referral will be recruited from five treatment centers. Clinical effectiveness and cost-effectiveness will be measured before treatment, directly after treatment, at 6 and at 12 months follow-up. In order to rate process evaluation, patient experiences and the degree to which treatments are implemented according to protocol will be measured. In order to assess the quality of life and the achievement of personalized goals, interviews will be conducted at the end of treatment. Data will be analyzed, using a regression-based approach to mixed modelling, multivariate sensitivity analyses and coding trees for qualitative data. We hypothesize GST to be superior to CBT-E in terms of clinical effectiveness and cost-effectiveness for patients who do not show a rapid response to the first 4 weeks of a CBT-E treatment. DISCUSSION: To our knowledge, this is the first study protocol describing a multicenter RCT to explore the three aforementioned objectives. Related risks in performing the study protocol have been outlined. The expected findings may serve as a guide for healthcare stakeholders to optimize ED care trajectories. TRIAL REGISTRATION: clinicaltrials.gov (NCT05812950).

There is nothing as inconsistent as the OSFED diagnostic criteria.

Atypical anorexia nervosa (AAN), purging disorder (PD), night eating syndrome (NES), and subthreshold bulimia nervosa and binge-eating disorder (Sub-BN/BED) are the five categories that comprise the 'Other Specified Feeding or Eating Disorder' (OSFED) category in the Diagnostic and Statistical Manual for Mental Disorders (DSM-5). In this review, we examine problems with the diagnostic criteria that are currently proposed for the five OSFED types. We conclude that the existing diagnostic criteria for OSFED are deficient and fall short of accurately describing the complexity and individuality of those with these eating disorders (EDs). Therefore, to enhance the quality of life of people with OSFED, diagnostic criteria for the condition should be applied uniformly in clinical and research settings.

Naturalistic symptom trajectories of atypical anorexia nervosa, anorexia nervosa, and bulimia nervosa in a prospective cohort study of United States college students.

OBJECTIVE: Research on the natural course of symptoms of atypical anorexia nervosa (AN) relative to AN and bulimia nervosa (BN) is limited yet needed to inform nosology and improve understanding of atypical AN. This study aimed to 1) characterize trajectories of eating disorder and internalizing (anxiety, depression) symptoms in college students with and without a history of atypical AN, AN, and BN; and 2) compare sex and race/ethnicity distributions across groups. METHOD: United States college students who participated in Spit for Science™, a prospective cohort study, were classified as having a history of atypical AN (n = 125), AN (n = 160), BN (n = 617), or as non-eating-disorder controls (NCs, n = 5876). Generalized and linear mixed-effects models assessed group differences in eating and internalizing symptom trajectories, and logistic regression compared groups on sex and race/ethnicity distributions. RESULTS: Atypical AN participants demonstrated elevated eating disorder and internalizing symptoms compared to NCs during college, but less severe symptoms than AN and BN participants. Although all eating disorder groups showed signs of improvement in fasting and driven exercise, purging and depression remained elevated. Atypical AN participants showed increasing anxiety and stable binge-eating trajectories compared to AN and/or BN participants. The atypical AN group comprised significantly more people of color than the AN group. DISCUSSION: Findings underscore that atypical AN is a severe psychiatric disorder. As atypical AN may present as less severe than AN and BN and disproportionately affects people of color, clinicians should be mindful of biases that could delay diagnosis and care. PUBLIC SIGNIFICANCE: College students with histories of atypical AN, AN, and BN demonstrated improvements in fasting and driven exercise and stable purging and depression levels. Atypical AN students showed worsening anxiety and stable binge-eating trajectories compared to favorable changes among AN and BN students. A higher percentage of atypical AN (vs. AN) students were people of color. Findings may improve the detection of atypical AN in college students.

Lower region-specific gray matter volume in females with atypical anorexia nervosa and anorexia nervosa.

OBJECTIVE: Few studies have focused on brain structure in atypical anorexia nervosa (atypical AN). This study investigates differences in gray matter volume (GMV) between females with anorexia nervosa (AN) and atypical AN, and healthy controls (HC). METHOD: Structural magnetic resonance imaging data were acquired for 37 AN, 23 atypical AN, and 41 HC female participants. Freesurfer was used to extract GMV, cortical thickness, and surface area for six brain lobes and associated cortical regions of interest (ROI). Primary analyses employed linear mixed-effects models to compare group differences in lobar GMV, followed by secondary analyses on ROIs within significant lobes. We also explored relationships between cortical gray matter and both body mass index (BMI) and symptom severity. RESULTS: Our primary analyses revealed significant lower GMV in frontal, temporal and parietal areas (FDR < .05) in AN and atypical AN when compared to HC. Lobar GMV comparisons were non-significant between atypical AN and AN. The parietal lobe exhibited the greatest proportion of affected cortical ROIs in both AN versus HC and atypical AN versus HC. BMI, but not symptom severity, was found to be associated with cortical GMV in the parietal, frontal, temporal, and cingulate lobes. No significant differences were observed in cortical thickness or surface area. DISCUSSION: We observed lower GMV in frontal, temporal, and parietal areas, when compared to HC, but no differences between AN and atypical AN. This indicates potentially overlapping structural phenotypes between these disorders and evidence of brain changes among those who are not below the clinical underweight threshold. PUBLIC SIGNIFICANCE: Despite individuals with atypical anorexia nervosa presenting above the clinical weight threshold, lower cortical gray matter volume was observed in partial, temporal, and frontal cortices, compared to healthy individuals. No significant differences were found in cortical gray matter volume between anorexia nervosa and atypical anorexia nervosa. This underscores the importance of continuing to assess and target weight gain in clinical care, even for those who are presenting above the low-weight clinical criteria.

Differentiation between atypical anorexia nervosa and anorexia nervosa using machine learning.

OBJECTIVE: Body mass index (BMI) is the primary criterion differentiating anorexia nervosa (AN) and atypical anorexia nervosa despite prior literature indicating few differences between disorders. Machine learning (ML) classification provides us an efficient means of accurately distinguishing between two meaningful classes given any number of features. The aim of the present study was to determine if ML algorithms can accurately distinguish AN and atypical AN given an ensemble of features excluding BMI, and if not, if the inclusion of BMI enables ML to accurately classify between the two. METHODS: Using an aggregate sample from seven studies consisting of individuals with AN and atypical AN who completed baseline questionnaires (N = 448), we used logistic regression, decision tree, and random forest ML classification models each trained on two datasets, one containing demographic, eating disorder, and comorbid features without BMI, and one retaining all features and BMI. RESULTS: Model performance for all algorithms trained with BMI as a feature was deemed acceptable (mean accuracy = 74.98%, mean area under the receiving operating characteristics curve [AUC] = 74.75%), whereas model performance diminished without BMI (mean accuracy = 59.37%, mean AUC = 59.98%). DISCUSSION: Model performance was acceptable, but not strong, if BMI was included as a feature; no other features meaningfully improved classification. When BMI was excluded, ML algorithms performed poorly at classifying cases of AN and atypical AN when considering other demographic and clinical characteristics. Results suggest a reconceptualization of atypical AN should be considered. PUBLIC SIGNIFICANCE: There is a growing debate about the differences between anorexia nervosa and atypical anorexia nervosa as their diagnostic differentiation relies on BMI despite being similar otherwise. We aimed to see if machine learning could distinguish between the two disorders and found accurate classification only if BMI was used as a feature. This finding calls into question the need to differentiate between the two disorders.

Is there a basis for a weight cut-off point? A large-scale investigation of atypical anorexia and anorexia nervosa subtypes among patients at a residential treatment centre.

OBJECTIVE: There is debate surrounding how to differentiate between anorexia nervosa (AN) and atypical AN (atypAN) as diagnostic entities, and whether a distinction based on BMI is warranted. Better understanding eating disorder (ED) and emotional symptoms across atypAN and AN subtypes [AN-restricting (AN-R), AN-binge/purge (AN-BP)], with and without controlling for BMI, can elucidate how atypAN differs from AN subtypes and whether there is a basis for a BMI cut-off. METHODS: 1810 female patients at an ED treatment centre completed intake surveys. ANCOVAs assessed differences across AN-R (n = 853), AN-BP (n = 726), and atypAN (n = 231) groups on ED, depressive, and anxiety symptoms, anxiety sensitivity, experiential avoidance, and mindfulness, with and without controlling for BMI. RESULTS: Relative to AN-R, atypAN and AN-BP groups endorsed significantly higher ED and depressive symptoms, anxiety sensitivity, experiential avoidance, and significantly lower mindfulness (all p < 0.001), but atypAN and AN-BP groups did not differ from one another. When controlling for BMI, all previously significant differences between atypAN and AN-R did not remain significant. CONCLUSION: Individuals with atypAN who have a higher BMI experience more pronounced ED and emotional symptoms, suggesting that relying solely on BMI as a marker of illness severity may be problematic.

Time to revisit the definition of atypical anorexia nervosa.

In this special issue, international researchers investigate how atypical anorexia nervosa (atypical AN) differs from anorexia nervosa (AN) and other eating disorders with respect to demographics, psychological and physiological morbidity, as well as treatment course and outcome. Manuscripts in this special issue report that atypical AN is associated with substantial medical and psychological morbidity, and the majority of studies find few differences between atypical AN and AN. While much remains to be learned about the long-term course and treatment response of individuals with atypical AN to psychological and pharmacological interventions, the evidence supports conceptualization of atypical AN as part of a spectrum-based restrictive eating disorder. These findings together with the potentially stigmatizing use of the term "atypical" suggest it may be time to revise the existing definition of atypical AN.

Emotion coaching skills as an augmentation to family-based therapy for adolescents with anorexia nervosa: A pilot effectiveness study with families with high expressed emotion.

OBJECTIVE: To examine the feasibility and acceptability of augmenting family-based treatment (FBT) for adolescents with anorexia nervosa (AN) or atypical anorexia nervosa (AAN) with a parent emotion coaching intervention (EC) focused on reducing parent expressed emotion. METHOD: In this pilot effectiveness trial, families of adolescents with AN/AAN exhibiting high expressed emotion received standard FBT with either (1) EC group or (2) support group (an attention control condition focused on psychoeducation). RESULTS: Forty-one adolescents with AN or AAN were recruited (88% female, Mage = 14.9 ± 1.6 years, 95% White: Non-Hispanic, 1% White: Hispanic, 1% Bi-racial: Asian). Most study adolescents were diagnosed with AN (59%) while 41% were diagnosed with AAN. Participating parents were predominantly mothers (95%). Recruitment and retention rates were moderately high (76% and 71%, respectively). High acceptability and feasibility ratings were obtained from parents and interventionists with 100% reporting the EC intervention was "beneficial"-"very beneficial." The FBT + EC group demonstrated higher parental warmth scores at post-treatment compared to the control group (standardized effect size difference, d = 1.58), which was maintained at 3-month follow-up. Finally, at post-treatment, the FBT + EC group demonstrated higher rates of full remission from AN/AAN (40%) compared to FBT + support (27%), and were nine times more likely to be weight restored by 3-month follow-up. DISCUSSION: Augmenting FBT with emotion coaching for parents with high expressed emotion is acceptable, feasible, and demonstrates preliminary effectiveness. PUBLIC SIGNIFICANCE: Family based treatment for AN/AAN is the recommended treatment for youth but families with high criticism/low warmth are less likely to respond to this treatment. Adding a parent emotion coaching group (EC) where parents learn to talk to their adolescents about tough emotions is feasible and well-liked by families.

Short-term outcomes of the study of refeeding to optimize inpatient gains for patients with atypical anorexia nervosa.

OBJECTIVE: The StRONG trial demonstrated the safety and efficacy of higher calorie refeeding (HCR) in hospitalized adolescents and young adults with malnutrition secondary to restrictive eating disorders. Here we compare refeeding outcomes in patients with atypical anorexia nervosa (atypical AN) versus anorexia nervosa (AN) and examine the impact of caloric dose. METHOD: Patients were enrolled upon admission and randomized to meal-based HCR, beginning 2000 kcal/day and advancing 200 kcal/day, or lower calorie refeeding (LCR), beginning 1400 kcal/day and advancing 200 kcal every other day. Atypical AN was defined as %median BMI (mBMI) > 85. Independent t-tests compared groups; multivariable linear and logistic regressions examined caloric dose (kcal/kg body weight). RESULTS: Among n = 111, mean ± SD age was 16.5 ± 2.5 yrs; 43% had atypical AN. Compared to AN, atypical AN had slower heart rate restoration (8.7 ± 4.0 days vs. 6.5 ± 3.9 days, p = .008, Cohen's d = -.56), less weight gain (3.1 ± 5.9%mBMI vs. 5.4 ± 2.9%mBMI, p < .001, Cohen's d = .51) and greater hypomagnesemia (29% vs. 11%, p = .03, OR = 3.29). These suboptimal outcomes were predicted by insufficient caloric dose (32.4 ± 6.9 kcal/kg in atypical AN vs. 43.4 ± 9.8 kcal/kg in AN, p < .001, Cohen's d = 1.27). For every 10 kcal/kg increase, heart rate was restored 1.7 days (1.0, 2.5) faster (p < .001), weight gain was 1.6%mBMI (.8, 2.4) greater (p < .001), and hypomagnesemia odds were 70% (12, 128) lower (p = .02). DISCUSSION: Although HCR is more efficacious than LCR for refeeding in AN, it contributes to underfeeding in atypical AN by providing an insufficient caloric dose relative to the greater body weight in this diagnostic group. PUBLIC SIGNIFICANCE: The StRONG trial previously demonstrated the efficacy and safety of higher calorie refeeding in patients with malnutrition due to restrictive eating disorders. Here we show that higher calorie refeeding contributes to underfeeding in patients with atypical anorexia nervosa, including poor weight gain and longer time to restore medical stability. These findings indicate these patients need more calories to support nutritional rehabilitation in hospital.

Clinical characteristics of hospitalized male adolescents and young adults with atypical anorexia nervosa.

OBJECTIVE: To describe the clinical characteristics of male adolescents and young adults hospitalized for medical complications of atypical anorexia nervosa (atypical AN) and to compare their clinical characteristics with females with atypical AN and males with anorexia nervosa (AN). METHOD: A retrospective review of electronic medical records for patients with atypical AN and AN aged 9-25 admitted to the UCSF Eating Disorders Program from May 2012 to August 2020 was conducted. RESULTS: Among 21 males with atypical AN (mean age 15.1 ± 2.7, mean %mBMI 102.0 ± 11.8), medical complications evidenced by admission laboratory values included anemia (52.9%), vitamin D insufficiency/deficiency (52.6%), and zinc deficiency (31.6%). Compared with females with atypical AN (n = 69), males with atypical AN had longer length of stay (11.4 vs 8.4 days, p = .004), higher prescribed kcal at discharge (4114 vs 3045 kcal, p < .001), lower heart rate nadir (40.0 vs 45.8, p = .038), higher aspartate transaminase (AST, 37.9 vs 26.2 U/L, p = .032), higher alanine transaminase (ALT, 30.6 vs 18.3 U/L, p = .005), and higher rates of anemia (52.9% vs 19.4%, p = .005), with no differences in vitamin D, zinc, and vital signs. Compared with males with AN (n = 40), males with atypical AN had no significant differences in vital signs or laboratory assessments during the hospitalization. DISCUSSION: Atypical AN in males leads to significant medical comorbidity, and males with atypical AN require longer hospital stays compared to females with atypical AN. Rates of abnormal vital signs and abnormal serum laboratory values during hospital admissions do not differ in males with atypical AN compared to AN. PUBLIC SIGNIFICANCE: Adolescent and young adult males with atypical anorexia nervosa experience significant medical complications. Males with atypical anorexia nervosa had longer hospitalizations and higher prescribed nutrition at discharge than females. Medical complications of atypical anorexia nervosa in male adolescents and young adults were generally equal to those of male adolescents and young adults with anorexia nervosa. Clinicians should be aware of unique medical complications of males with atypical anorexia nervosa.

Understanding community provider practices in diagnosing and treating atypical anorexia nervosa: A mixed methods study.

OBJECTIVE: There is a lack of consensus in defining "significant weight loss" when diagnosing atypical anorexia nervosa (atypical AN) and no guidelines exist for setting target weight (TW). The current study aimed to identify community providers' practices related to the diagnosis of atypical AN and the determination of TW. A secondary aim was to evaluate whether professional discipline impacted "significant weight loss" definitions. METHOD: A variety of providers (N = 141; 96.4% female) completed an online survey pertaining to diagnostic and treatment practices with atypical AN. Descriptive statistics were computed to characterize provider-based practices and Fisher's exact tests were used to test for differences in diagnostic practices by professional discipline. Thematic analysis was used to examine open-ended questions. RESULTS: Most (63.97%) providers diagnosed atypical AN in the absence of any weight loss if other AN criteria were met, but doctoral-level psychologists and medical professionals were less likely to do so compared to nutritional or other mental health professionals. Most providers found weight gain was only sometimes necessary for atypical AN recovery. Qualitative responses revealed providers found atypical AN to be a stigmatizing label that was not taken seriously. Providers preferred to use an individualized approach focused on behaviors, rather than weight when diagnosing and treating atypical AN. DISCUSSION: Lack of diagnostic clarity and concrete treatment guidelines for atypical AN may result in substantial deviations from the DSM-5-TR criteria in real-world practice. Clinically useful diagnostic definitions for restrictive eating disorders and evidence-based treatment guidelines for TW and/or other relevant recovery metrics are needed. PUBLIC SIGNIFICANCE: The current study found variability in how community providers diagnose and determine target recovery weight for atypical anorexia nervosa (atypical AN). Many providers viewed the diagnosis of atypical AN as stigmatizing and preferred to focus on behaviors, rather than weight. This study underscores the importance of creating a clinically useful diagnostic definition and guidelines for recovery for atypical AN backed by empirical evidence that providers may implement in practice.

Examining the placement of atypical anorexia nervosa in the eating disorder diagnostic hierarchy relative to bulimia nervosa and binge-eating disorder.

OBJECTIVE: Some individuals meet the criteria for atypical anorexia nervosa and another eating disorder simultaneously. The current study evaluated whether allowing a diagnosis of atypical anorexia nervosa to supersede a diagnosis of bulimia nervosa (BN) or binge-eating disorder (BED) provided additional information on psychological functioning. METHODS: Archival data from 650 university students (87.7% female, 69.4% white) who met Eating Disorder Diagnostic Survey for DSM-5 eating disorder criteria and completed questionnaires assessing quality of life, eating disorder-related impairment, and/or eating pathology at a single time point. Separate regression models used diagnostic category to predict quality of life and impairment. Two diagnostic schemes were used: the DSM-5 diagnostic scheme and an alternative scheme where atypical anorexia nervosa superseded all diagnoses except anorexia nervosa. Model fit was compared using the Davidson-Mackinnon J test. Analyses were pre-registered (https://osf.io/2ejcd). RESULTS: Allowing an atypical anorexia nervosa diagnosis to supersede a BN or BED diagnosis provided better fit to the data for eating disorder-related impairment (p = .02; n = 271), but not physical, psychological, or social quality of life (p's ≥ .33; n = 306). Allowing an atypical anorexia nervosa diagnosis to supersede a BN or BED diagnosis provided a better fit in cross-sectional models predicting purging (p = .02; n = 638), but not body dissatisfaction, binge eating, restricting, or excessive exercise (p's ≥ .08; n's = 633-647). DISCUSSION: The current data support retaining the DSM-5 diagnostic scheme. More longitudinal work is needed to understand the predictive validity of the atypical anorexia nervosa diagnosis. PUBLIC SIGNIFICANCE: The current study examined how changes to the diagnostic categories for eating disorders may change how diagnoses are associated with quality of life and impairment. Overall, findings suggest that the diagnostic hierarchy should be maintained.

An examination of adults with atypical anorexia nervosa at admission to treatment at higher levels of care: An attempt to increase diagnostic clarity.

OBJECTIVE: Anorexia nervosa (AN) is a serious illness with a high mortality rate and multiple physiological complications. The vague definition of atypical AN allows for subjective interpretation. This retrospective study aimed to focus future research on the operational definition of atypical AN by examining four factors associated with atypical AN at admission to higher level of care treatment. METHODS: Adults with atypical AN (n = 69) were examined within sample analyses among four groups: (1) >10% versus ≤10% weight loss; (2) weight loss within the previous 3 months versus >3 months; (3) engaging in purging behaviors versus absence of purging behaviors; and (4) endorsing versus not endorsing significant cognitive aspects of AN. RESULTS: Patients with atypical AN endorsed elevated ED cognitions on the Eating Disorder Examination-Questionnaire and depressive symptoms; a lack of association was found between weight loss severity and weight loss time frame with depressive symptoms, eating concern, and restraint. Purging behavior was associated with a higher expected body weight percentage (%EBW) and dietary restraint, while greater AN cognitions were associated with a higher EBW and weight loss percentage. Few patients demonstrated bradycardia, hypophosphatemia, or amenorrhea. DISCUSSION: This study demonstrated the severity of ED cognitions and depressive symptoms in this atypical AN sample and provided directions for future studies in the nosology of atypical AN. It may be important to distinguish between individuals with atypical AN who are purging and those who are not. Atypical AN was associated with a low frequency of physiological disturbances. PUBLIC SIGNIFICANCE: This study provides further clarification regarding the operational definition of atypical AN; currently, a constellation of symptoms under Other Specified Feeding or Eating Disorders. This study was consistent with previous research in reporting severe eating disorder cognitions in adults with atypical AN, and noted the potential importance of distinguishing a purging distinction. A minority of patients in this study had physiological impairments.