Harnessing precision nutrition to individualize weight restoration in anorexia nervosa.

Anorexia nervosa (AN) is a severe psychiatric disorder for which effective treatment and sustained recovery are contingent upon successful weight restoration, yet the efficacy of existing treatments is suboptimal. This narrative review considers the potential of precision nutrition for tailoring dietary interventions to individual characteristics to enhance acute and longer-term weight outcomes in AN. We review key factors that drive variation in nutritional requirements, including energy expenditure, fecal energy loss, the gut microbiota, genetic factors, and psychiatric comorbidities. Although scientific evidence supporting precision nutrition in AN is limited, preliminary findings suggest that individualized nutrition therapies, particularly those considering duration of illness and the gut microbiota, may augment weight gain. Some patients may benefit from microbiota-directed dietary plans that focus on restoring microbial diversity, keystone taxa, or functions that promote energy absorption, which could enhance weight restoration-although stronger evidence is needed to support this approach. Furthermore, accounting for psychiatric comorbidities such as depression and anxiety as well as genetic factors influencing metabolism may help refine nutrition prescriptions improving upon existing energy estimation equations, which were not developed for patients with AN. Given the reliance on large sample sizes, costly data collection, and the need for computationally intensive artificial intelligence algorithms to assimilate deep phenotypes into personalized interventions, we highlight practical considerations related to the implementation of precision nutrition approaches in clinical practice. More research is needed to identify which factors, including metabolic profiles, genetic markers, demographics, and habitual lifestyle behaviors, are most critical to target for individualizing weight restoration, and whether personalized recommendations can be practicably applied to improve and sustain patient recovery from this debilitating disorder with high relapse and mortality rates.