Serum Leptin in Youth and Young Adults With Avoidant/Restrictive Food Intake Disorder Across the Weight Spectrum

Avoidant/restrictive food intake disorder (ARFID) involves restrictive eating driven by sensory sensitivity, low interest in food, or fear of negative consequences of eating. ARFID affects males and females equally and presents across the weight spectrum. Leptin, an anorexigenic hormone linked to adiposity, may contribute to low hunger and early satiety in ARFID. Prior findings indicate low leptin levels in low-weight females with ARFID; however, the role of leptin in ARFID across weight status and sex remains unknown. We hypothesized that youth with full/subthreshold ARFID, including a subgroup of low-weight males, would exhibit lower fasting leptin levels than healthy controls (HCs). We explored cross-sectional and longitudinal associations between leptin and clinical characteristics.

Participants were youth aged 10-23 years (BMI percentile M [SD] = 41.4 (33.6)) with full/subthreshold ARFID (n = 95; 49.5% female) and HCs (n = 28; 50.0% female). At baseline, participants completed questionnaires, a fasted blood draw, and a diagnostic interview for ARFID, readministered at 1- and 2year follow-ups.

Leptin levels did not differ between ARFID and HC groups. Low-weight ARFID males had significantly lower leptin than HC males (η ² = 0.258); however, this difference was nonsignificant after adjusting for BMI percentile. Leptin showed medium-to-large positive associations with age, BMI, and anxiety but not appetite or ARFID severity. Baseline leptin did not predict symptom or weight changes longitudinally.

Hypoleptinemia was only evident in low-weight ARIFD and strongly correlated with BMI percentile. However, relationships with anxiety may suggest additional roles of leptin in underlying ARFID psychopathology. Findings should be replicated in larger, more representative samples.