The use of indirect calorimetry in patients with eating disorders: a scoping review

Background: Indirect calorimetry (IC) is the gold standard method for measuring energy expenditure to calculate an individual's nutritional requirements. However, literature is limited on its use in adults with eating disorders who are hospitalized due to medical instability and undergoing refeeding. Objective: The objective of this scoping review is to map the evidence regarding the use of IC for adults with eating disorders hospitalized due to medical instability. Methods: PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, and Cochrane Library were searched on April 18, 2024, to identify studies published in English reporting the use of IC in adult patients with eating disorders who are hospitalized and undergoing refeeding. There were no restrictions on publication date, and all eating disorder types were accepted. Article screening was conducted in 2 stages, and identified studies were independently screened by 2 reviewers to identify studies that met the inclusion criteria. Data extracted included study and population characteristics, eating disorder diagnosis, nutrition regimen, and IC protocol. Results: Searches yielded 641 articles for screening, with 19 studies included in the final review. There were 624 patients with eating disorders, all diagnosed with anorexia nervosa, with a body mass index range of 9.6 to 15.4 kg/m². Before IC measurements, patients fasted for ≥10 to 12 hours, and no adverse events regarding fasting were reported. Timelines of IC measurements during refeeding were variable, and it remains unclear what the most efficacious time to perform IC is if used to guide nutrition provision. Reporting on co-occurring mental health diagnoses and complexities and considerations when using IC in patients with eating disorders was scarce. Conclusions: There is a paucity of literature regarding practical considerations of using IC in adult patients hospitalized with eating disorders. Further research is required to inform the useful, sensitive, and robust use of IC in the target cohort.