Premorbid body weight predicts weight loss in both anorexia nervosa and atypical anorexia nervosa: Further support for a single underlying disorder

OBJECTIVE

For adolescents, DSM-5 differentiates anorexia nervosa (AN) and atypical AN with the 5th BMI-centile-for-age. We hypothesized that the diagnostic weight cut-off yields (i) lower weight loss in atypical AN and (ii) discrepant premorbid BMI distributions between the two disorders. Prior studies demonstrate that premorbid BMI predicts admission BMI and weight loss in patients with AN. We explore these relationships in atypical AN.

METHOD

Based on admission BMI-centile < or ≥5th, participants included 411 female adolescent inpatients with AN and 49 with atypical AN from our registry study. Regression analysis and t-tests statistically addressed our hypotheses and exploratory correlation analyses compared interrelationships between weight loss, admission BMI, and premorbid BMI in both disorders.

RESULTS

Weight loss in atypical AN was 5.6 kg lower than in AN upon adjustment for admission age, admission height, premorbid weight and duration of illness. Premorbid BMI-standard deviation scores differed by almost one between both disorders. Premorbid BMI and weight loss were strongly correlated in both AN and atypical AN.

DISCUSSION

Whereas the weight cut-off induces discrepancies in premorbid weight and adjusted weight loss, AN and atypical AN overall share strong weight-specific interrelationships that merit etiological consideration. Epidemiological and genetic associations between AN and low body weight may reflect a skewed premorbid BMI distribution. In combination with prior findings for similar psychological and medical characteristics in AN and atypical AN, our findings support a homogenous illness conceptualization. We propose that diagnostic subcategorization based on premorbid BMI, rather than admission BMI, may improve clinical validity.

PUBLIC SIGNIFICANCE

Because body weights of patients with AN must drop below the 5th BMI-centile per DSM-5, they will inherently require greater weight loss than their counterparts with atypical AN of the same sex, age, height and premorbid weight. Indeed, patients with atypical AN had a 5.6 kg lower weight loss after controlling for these variables. In comparison to the reference population, we found a lower and higher mean premorbid weight in patients with AN and atypical AN, respectively. Considering previous psychological and medical comparisons showing little differences between AN and atypical AN, we view a single disorder as the most parsimonious explanation. Etiological models need to particularly account for the strong relationship between weight loss and premorbid body weight.

Chuna manual therapy for the treatment of anorexia in children: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Anorexia in children can cause malnutrition, low immunity, growth retardation, and various secondary infections, resulting in a huge burden on society. In East Asia, Chuna manual therapy has been widely used for the treatment of childhood anorexia. We aimed to comprehensively evaluate the effects of Chuna manual therapy for treating childhood anorexia.

METHODS

Twelve databases were comprehensively searched from their inception to September 13, 2022. Only randomized controlled trials assessing Chuna manual therapy for the treatment of childhood anorexia were included. The methodological quality of the included studies was assessed using the Cochrane risk-of-bias tool. The quality of evidence for each main outcome was evaluated using the grading of recommendations assessment, development, and evaluation approach. A meta-analysis was performed, and the pooled data were presented as risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes.

RESULTS

Twenty-five RCTs involving 2230 participants were included. The meta-analysis showed that Chuna manual therapy had a higher total effective rate (TER) based on anorexia symptoms than that of lysine inositol and vitamin B12 (RR: 1.53, 95% CI: 1.28-1.84), multi-enzyme and multi-vitamin (RR: 1.21, 95% CI: 1.11-1.33), and zinc calcium gluconate (RR: 1.22, 95% CI: 1.06-1.39). There was no significant difference in total effective rate between Chuna manual therapy and zinc gluconate plus lysine. No adverse events associated with Chuna manual therapy were reported. Overall, the included studies had an unclear risk of bias, and the quality of evidence was generally moderate to low.

CONCLUSION

Current evidence showed that Chuna manual therapy may be effective and safe for improving anorexia symptoms, especially compared with lysine inositol and vitamin B12, multi-enzyme plus multi-vitamin, and zinc calcium gluconate. However, owing to the low methodological quality of the included studies, more rigorous, high-quality RCTs are required on this topic.

The effects of polyunsaturated fatty acid (PUFA) administration on the microbiome-gut-brain axis in adolescents with anorexia nervosa (the MiGBAN study): study protocol for a longitudinal, double-blind, randomized, placebo-controlled trial

Background

Anorexia nervosa (AN) is a severe psychiatric disease that often takes a chronic course due to insufficient treatment options. Emerging evidence on the gut-brain axis offers the opportunity to find innovative treatments for patients with psychiatric disorders. The gut microbiome of patients with AN shows profound alterations that do not completely disappear after weight rehabilitation. In previous studies, the administration of polyunsaturated fatty acids (PUFA) resulted in effects that might be beneficial in the treatment of AN, affecting the microbiome, body weight and executive functions. Therefore, the MiGBAN study aims to examine the effects of a nutritional supplementation with PUFA on the gut microbiome and body mass index (BMI) in patients with AN.

Methods

This is a longitudinal, double-blind, randomized, placebo-controlled trial. Within 2 years, 60 adolescent patients aged 12 to 19 years with AN will receive either PUFA or placebo for 6 months additional to treatment as usual. After 1 year, the long-term effect of PUFA on the gut microbiome and consecutively on BMI will be determined. Secondary outcomes include improvement of gastrointestinal symptoms, eating disorder psychopathology, and comorbidities. Additionally, the interaction of the gut microbiome with the brain (microbiome-gut-brain axis) will be studied by conducting MRI measurements to assess functional and morphological changes and neuropsychological assessments to describe cognitive functioning. Anti-inflammatory effects of PUFA in AN will be examined via serum inflammation and gut permeability markers. Our hypothesis is that PUFA administration will have positive effects on the gut microbiota and thus the treatment of AN by leading to a faster weight gain and a reduction of gastrointestinal problems and eating disorder psychopathology.

Discussion

Due to previously heterogeneous results, a systematic and longitudinal investigation of the microbiome-gut-brain axis in AN is essential. The current trial aims to further analyse this promising research field to identify new, effective therapeutic tools that could help improve the treatment and quality of life of patients. If this trial is successful and PUFA supplementation contributes to beneficial microbiome changes and a better treatment outcome, their administration would be a readily applicable additional component of multimodal AN treatment.

Trial registration

German Clinical Trials Register DRKS00017130. Registered on 12 November 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06413-7.

Help-seeking attitudes and behaviours among youth with eating disorders: a scoping review

BACKGROUND

Although early intervention is crucial in interrupting the development of eating disorders, little is currently known about help-seeking behaviours among individuals experiencing eating disorder symptoms. Given that eating disorders typically begin early in life, it is necessary to investigate the processes employed by children, adolescents, and emerging adults when seeking services for troubling symptoms. This is a growing concern as the COVID-19 pandemic has resulted in an increase in the number of individuals engaging in disordered eating behaviours. This scoping review explores the current state of the literature for evidence on how youth with eating disorder symptoms seek help, with the aim of better understanding how to identify and treat more individuals earlier.

METHODS

Using scoping review methodology, we searched seven databases for studies published from January 2000 to April 2021 that reported on help-seeking attitudes, behaviours, and healthcare utilization patterns for children and adolescents (< 18 years), emerging adults (18-25 years), and a mixture of these groups (< 25 years). Seven thousand, two hundred, and eighteen articles were identified for review. After duplicates were removed, three reviewers independently screened titles and abstracts and reviewed full-text articles. Findings related to help-seeking activity were extracted from the 62 articles that were ultimately included in this scoping review.

RESULTS

Study findings were summarized into help-seeking patterns (i.e., rates, types) as well as factors ranging from the individual level to society that influenced help-seeking behaviour. Many youth meeting eating disorder criteria were not seeking help. Notable barriers to help-seeking included poor mental health literacy, experiences with healthcare providers who failed to detect and lacked knowledge about eating disorders, minimal support from family and friends, and stigma surrounding eating disorders and help-seeking for mental health concerns.

CONCLUSIONS

The results of this scoping review can be used to inform early intervention and health promotion program development. Future research should focus on the help-seeking attitudes and activities among underrepresented groups with eating disorders (e.g., men, ethnic and gender minorities), the perspectives of family and other supporters in the help-seeking process for youth, and retrospective accounts from adults with lived experience of an eating disorder. Plain English summary Addressing and interrupting eating disorder-related thoughts and behaviours as soon as possible, with the help of a mental health professional, leads to better outcomes for youth struggling with an eating disorder. However, little is known about what prompts youth to talk about their weight, body, or eating concerns with someone-like their parent, friend, teacher, guidance counsellor, or primary care practitioner. This review explores the available published research on help-seeking patterns and preferences among youth with eating disorder concerns. Our team followed a standardized process to find 62 relevant articles for this paper. Of note, many young people who reported eating disorder concerns were not seeking help for themselves. Feeling supported by family and their primary care provider, understanding the signs of an eating disorder, and not feeling shame for reaching out for help reportedly led youth to speak up about their concerns. The findings have clinical implications for learning effective ways to help youth feel safe to speak freely about their eating disorder-related concerns, which enhances the chances of intervening early and catching symptoms before they worsen.

Reasons for admission and variance of body weight at referral in female inpatients with anorexia nervosa in Germany

BACKGROUND

Body mass index (BMI) at hospital admission in patients with anorexia nervosa (AN) represents a prognostic marker for mortality, chronicity and future body weight. The current study focused on the associations between BMI standard deviation score (BMI-SDS) at admission and reasons for seeking inpatient treatment. Further interest was given to the relationship between premorbid weight and weight at admission, as well as the effect of both weight at referral and reasons for admission on treatment outcome.

METHODS

Data ascertained in the German Register of Children and Adolescents with AN were analysed to assess the parental and patient overlap for 23 predefined reasons for admission, using factor analyses and regressions models.

RESULTS

Complete parent-patient data sets were available for 360 patients out of 769. The highest consensus rates between parents and patients were obtained for weight and eating behavior related reasons and hyperactivity. Based on factor analysis, four factors emerged. Premorbid BMI-SDS, age and 'low body weight' as stated by patients or parents explained almost 40% of the variance of the BMI-SDS at admission.

CONCLUSIONS

Results underscore the relevance of age and premorbid BMI for BMI at admission. Only single reasons for admission explained further variance, with 'low body weight' having the largest effect. Approximately 40% of the variance of BMI-SDS was explained. For the first time, the effect of premorbid BMI for BMI at admission was robustly demonstrated in a multicenter study. Of the variance in BMI-SDS at discharge, our model could explain 37%, with reasons for admission having a small effect. Further investigation of the reasons for admission would be worthwhile to improve treatment and prognosis.

The development and psychometric evaluation of FABIANA-checklist: a scale to assess factors influencing treatment initiation in anorexia nervosa

BACKGROUND

A long duration of untreated illness (DUI) is an unfavorable prognostic factor in anorexia nervosa (AN) and is associated with chronic illness progression. Although previous preventive measures aimed at reducing DUI and thus improving short- and long-term treatment outcomes have been partially successful, a better understanding of the factors involved in the sensitive phase prior to treatment initiation is needed. To date, there is no validated instrument available to assess these factors specifically for patients with AN. The FABIANA-project (Facilitators and barriers in anorexia nervosa treatment initiation) aims at identifying predictors of the DUI in order to target preventive measures better in the future. As part of this project, the FABIANA-checklist was developed, based on a multi-informant perspective and a multimodal bottom-up approach. The present study focusses on the process of item generation, item selection and psychometric validation of the checklist.

METHODS

Based upon a previous qualitative study, an initial set of 73 items was generated for the most frequently mentioned facilitators and barriers of treatment initiation in AN. After a process of consensual rating and cognitive pre-testing, the resulting 25-item version of the FABIANA-checklist was provided to a sample of female patients (N = 75), aged ≥ 14 years with AN that underwent their first psychotherapeutic treatment in the last 12 months. After item analysis, dimensionality of the final version of the FABIANA-checklist was tested by Principal Component Analysis (PCA). We evaluated construct validity assuming correlations with related constructs, such as perceived social support (F-SozU), support in the health care system (PACIC-5A), illness perception and coping (BIPQ).

RESULTS

We included 54 adult and 21 adolescent patients with AN, aged on average 21.4 years. Average BMI was 15.5 kg/m², age of onset was 19.2 years and average DUI was 2.25 years. After item analysis, 7 items were excluded. The PCA of the 18-item-FABIANA-checklist yielded six components explaining 62.64% of the total variance. Overall internal consistency was acceptable (Cronbach's α = .76) and construct validity was satisfactory for 14 out of 18 items. Two consistent components emerged: "primary care perceived as supportive and competent" (23.33%) and "emotional and practical support from relatives" (9.98%). With regard to the other components, the heterogeneity of the items led to unsatisfactory internal consistency, single item loading and in part ambiguous interpretability.

CONCLUSIONS

The FABIANA-checklist is a valid instrument to assess factors involved in the process of treatment initiation of patients with AN. Psychometrics and dimensionality testing suggests that experienced emotional and practical support from the primary health care system and close relatives are main components. The results indicate that a differentiated assessment at item level is appropriate. In order to quantify the relative importance of the factors and to derive recommendations on early-intervention approaches, the predictive effect of the FABIANA-items on the DUI will be determined in a subsequent study which will further include the perspective of relatives and primary caregivers. Trial registration Clinical Trials.gov Identifier: NCT03713541: https://clinicaltrials.gov/ct2/show/NCT03713541 .

Efficacy and safety of pediatric massage in the treatment of anorexia: A protocol for systematic review and meta-analysis

BACKGROUND

Anorexia is a common and frequent disease in clinical pediatrics. It refers to a chronic digestive disorder syndrome with loss of appetite or disappearance and reduced food intake. The incidence of anorexia in children is very high, if not timely, safe and effective treatment, will have a huge impact on the growth and development of children. The toxic side effects of related treatment drugs often worry clinicians. Pediatric massage is external therapy, with green, safe and effective characteristics, lack of evidence-based medicine evidence support. A systematic evaluation and meta-analysis of the safety and efficacy of pediatric massage in the treatment of anorexia will be carried out in this paper to provide a powerful evidence.

METHODS

We'll retrieve 8 electronic databases, including the PubMed, Embase, Cochrane Library, Web Of Science, Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), Wanfang Database (WF), China Science Journal Database (VIP), the retrieval date was established from the database to March 2021. The authors will screen the study independently, Extracting data, and through Coch bias tools to assess the quality hazards of methods. RevmanV.5.3 software will be used for statistical analysis.

RESULTS

The results of this study need to be obtained after the completion of this program.

CONCLUSIONS

The conclusion of this study will confirm the efficacy and safety of pediatric massage in the treatment of anorexia, and provide reliable evidence for clinical selection of pediatric massage in the treatment of anorexia.

ETHICS AND DISSEMINATION

This study does not need to be reviewed by the Ethics Committee, because this paper is not a clinical study or a related experimental study, and this paper is only a literature study.

INPLASY REGISTRATION NUMBER

INPLASY202130050.

Can you find the right support for children, adolescents and young adults with anorexia nervosa: Access to age-appropriate care systems in various healthcare systems

OBJECTIVE

Anorexia nervosa (AN) often has its onset in childhood or adolescence. However, there is insufficient knowledge regarding access to and utilisation of age-specific clinical diagnostics and treatment.

METHODS

A literature review covering the last 10 years was conducted to provide a narrative review of the current state of research on the detection and treatment of young patients with AN in primary and secondary care.

RESULTS

Most articles were of Western European or US origin. Timely diagnosis of the eating disorder (ED) and treatment options more often depend on the structure and quality of the national health care system than on scientific evidence. Regular paediatric health check-ups and age-appropriate eating disorder services appear to facilitate early diagnosis. Age-specific treatment that also involves the carers is often associated with a higher continuity of care and a better outcome. Although many adolescents require an extension of treatment into young adulthood, individual and health care system-related obstacles in many countries prevent a smooth transition.

CONCLUSION

To improve outcomes in childhood and adolescent AN, age-specific and timely diagnostic and therapeutic procedures are urgently needed.

Age dependency of body mass index distribution in childhood and adolescent inpatients with anorexia nervosa with a focus on DSM-5 and ICD-11 weight criteria and severity specifiers

Both DSM-5 and ICD-11 have provided weight cut-offs and severity specifiers for the diagnosis of anorexia nervosa (AN) in childhood, adolescence and adulthood. The aims of the current study focusing on inpatients aged < 19 years were to assess (1) the relationship between age and body mass index (BMI; kg/m²), BMI-centiles, BMI-standard deviation scores (BMI-SDS) and body height-SDS at referral, (2) the percentages of patients fulfilling the DSM-5 and ICD-11 weight criteria and severity categories for AN, and (3) the validity of the AN severity specifiers via analysis of both weight related data at discharge and inpatient treatment duration. The German Registry for Anorexia Nervosa encompassed complete data sets for 469 female patients (mean age = 15.2 years; range 8.9-18.9 years) with a diagnosis of AN (n = 404) or atypical AN (n = 65), who were ascertained at 16 German child and adolescent psychiatric hospitals. BMI at referral increased up to age 15 to subsequently plateau. Approximately one tenth of all patients with AN had a BMI above the fifth centile. The ICD-11 specifier based on a BMI-centile of 0.3 for childhood and adolescent AN entailed two equally sized groups of patients. Discharge data revealed limited validity of the specifiers. Height-SDS was not correlated with age thus stunting had no impact on our data. We corroborate the evidence to use the tenth instead of the fifth BMI-centile as the weight criterion in children and adolescents. Weight criteria should not entail major diagnostic shifts during the transition from adolescence to adulthood. The severity specifiers based on BMI or BMI-centiles do not seem to have substantial clinical validity.

Facilitators and barriers to supporting young people with eating disorders during their transition to, and time at, university: An exploration of clinicians' perspectives

BACKGROUND

Eating disorders (EDs) are common in student populations and present formidable challenges as to how best to treat and support these young people, especially at points of transition. Yet research exploring these challenges is lacking, particularly from the perspective of those providing treatment and support.

METHODS

A qualitative design was used to explore clinicians' perspectives of supporting students with EDs. Twelve clinicians from a large ED service in the United Kingdom participated in one-to-one semi-structured interviews. Data were analysed using thematic analysis.

RESULTS

Facilitators and barriers to supporting students with EDs fell into four overarching themes: Health System, University, Patient and Carer Factors. Reported facilitators were; ED service awareness, flexibility and resources, university as a motivator, and carer support. Reported barriers were; poor links and communication between institutions, the primary care system, poor university provision for and awareness of EDs, young people's denial and ambivalence, inconsistent implementation of guidelines, and carer anxiety.

CONCLUSIONS

The findings revealed challenges unique to the university transition, including the need for more collaborative working between healthcare and education institutions, improved training of non-specialised ED professionals, and the benefits of a flexible, adapted ED treatment approach specifically tailored to the unique needs of students with EDs.

'Therapists in action'-Home treatment in adolescent anorexia nervosa: A stepped care approach to shorten inpatient treatment

OBJECTIVE

It was the aim of this pilot study to apply a novel eating disorder (ED)-specific home treatment (HoT) to adolescents with anorexia nervosa (AN) and to investigate its feasibility, effects and safety.

METHOD

Twenty-two patients consecutively admitted to the hospital and fulfilling DSM-5 criteria for typical or atypical AN received HoT after 4-8 weeks of inpatient treatment. During the first two months of HoT, the patient and her family were visited on average three to four times per week, during the third and fourth months of HoT once or twice a week by a multi-professional team. Body mass index, ED and general psychopathology, quality of life and treatment satisfaction were assessed in the patients at admission, start and end of HoT and the 1-year follow-up as well as carers' skills and burden.

RESULTS

The majority of patients successfully achieved target weight within HoT and maintained it successfully at the 1-year follow-up. ED and general psychopathology in the patients and carers' skills improved significantly associated with a high treatment satisfaction.

CONCLUSIONS

HoT seems to be a promising new tool to improve outcome in adolescent AN and to reduce time of hospitalisation. Larger randomised controlled trials are needed to generalise these results.

Incontinence and constipation in adolescent patients with anorexia nervosa-Results of a multicenter study from a German web-based registry for children and adolescents with anorexia nervosa

OBJECTIVE

Nocturnal enuresis (NE), daytime urinary incontinence (DUI), and fecal incontinence (FI) are common disorders in childhood and are frequently accompanied by comorbid psychiatric disorders. Despite a high association between urinary and fecal incontinence with psychiatric and neurodevelopmental disorders, research on comorbidity between incontinence and anorexia nervosa (AN) remains scarce. Yet, it is well known that somatic consequences of AN include metabolic and gastrointestinal disorders. The study sought to assess the prevalence of incontinence and constipation in children and adolescents with AN and to examine associations of these two symptoms with body weight at admission and with BMI changes during inpatient treatment.

METHODS

Data collected between 2015 and 2017 by a multicenter German web-based registry for AN were analyzed. Three hundred and forty-eight patients with AN (96.3% female, mean age = 15.1 ± 1.8 years) were assessed regarding AN subtype, psychiatric comorbidity, body weight, incontinence, and constipation.

RESULTS

Overall, 27.6% of patients had constipation, 1.8% had NE and 1.8% DUI. Prevalence of constipation did not significantly differ between AN subtypes. Constipation did not lead to any significant differences in weight/BMI changes during inpatient treatment.

DISCUSSION

This is the largest study of incontinence and constipation in patients with AN, so far. Our results indicate that constipation is highly prevalent in adolescent patients with AN and reflects a clinically relevant condition. Despite, patients with AN do not have an increased prevalence of incontinence compared with the general population. Future studies should include medical examinations like ultrasound and physical examination of the lower abdomen to evaluate the severity of constipation.

Clinical Characteristics of Inpatients with Childhood vs. Adolescent Anorexia Nervosa

We aimed to compare the clinical data at first presentation to inpatient treatment of children (<14 years) vs. adolescents (≥14 years) with anorexia nervosa (AN), focusing on duration of illness before hospital admission and body mass index (BMI) at admission and discharge, proven predictors of the outcomes of adolescent AN. Clinical data at first admission and at discharge in 289 inpatients with AN (children: n = 72; adolescents: n = 217) from a German multicenter, web-based registry for consecutively enrolled patients with childhood and adolescent AN were analyzed. Inclusion criteria were a maximum age of 18 years, first inpatient treatment due to AN, and a BMI <10th BMI percentile at admission. Compared to adolescents, children with AN had a shorter duration of illness before admission (median: 6.0 months vs. 8.0 months, p = 0.004) and higher BMI percentiles at admission (median: 0.7 vs. 0.2, p = 0.004) as well as at discharge (median: 19.3 vs. 15.1, p = 0.011). Thus, in our study, children with AN exhibited clinical characteristics that have been associated with better outcomes, including higher admission and discharge BMI percentile. Future studies should examine whether these factors are actually associated with positive long-term outcomes in children.

Feeding and Eating Disorders in Children

This article provides an update based on recently published literature and expert consensus on the current state of knowledge regarding feeding and eating disorders in children aged 2 to 12 years. It covers the 6 main diagnostic categories-pica, rumination disorder, avoidant/restrictive food intake disorder, anorexia nervosa, bulimia nervosa, and binge eating disorder-discussing issues and findings specific to this age group. It highlights the need for ongoing research in a number of key areas, to include improved understanding of etiologic pathways, characterization of presenting disorders, and the development of standardized evidence-based assessment tools and treatment interventions.

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

Objective

Recent preliminary studies indicated a seasonal association of BMI at admission to inpatient treatment for anorexia nervosa (AN), indicating lower BMI in the cold season for restrictive AN. An impaired thermoregulation was proposed as the causal factor, based on findings in animal models of AN. However, findings regarding seasonality of BMI and physical activity levels in the general population indicate lower BMI and higher physical activity in summer than in winter. Therefore, we aimed to thoroughly replicate the findings regarding seasonality of BMI at admission in patients with AN in this study.

Method

AN subtype, age- and gender-standardized BMI scores (BMI-SDS) at admission, mean daily sunshine duration and ambient temperature at the residency of 304 adolescent inpatients with AN of the multi-center German AN registry were analyzed.

Results

A main effect of DSM-5 AN subtype was found (F(2,298) = 6.630, p = .002), indicating differences in BMI-SDS at admission between restrictive, binge/purge and subclinical AN. No main effect of season on BMI-SDS at admission was found (F(1,298) = 4.723, p = .025), but an interaction effect of DSM-5 subtype and season was obtained (F(2,298) = 6.625, p = .001). Post-hoc group analyses revealed a lower BMI-SDS in the warm season for restrictive AN with a non-significant small effect size (t(203.16) = 2.140, p = .033; Hedges′g = 0.28). Small correlations of mean ambient temperature (r = −.16) and daily sunshine duration (r = −.22) with BMI-SDS in restrictive AN were found. However, the data were widely scattered.

Conclusions

Our findings are contrary to previous studies and question the thermoregulatory hypothesis, indicating that seasonality in AN is more complex and might be subject to other biological or psychological factors, for example physical activity or body dissatisfaction. Our results indicate only a small clinical relevance of seasonal associations of BMI-SDS merely at admission. Longitudinal studies investigating within-subject seasonal changes might be more promising to assess seasonality in AN and of higher clinical relevance.