OBJECTIVE: The primary aim of this study was to examine sex differences in energy availability (EA) and its relationships with disordered eating, compulsive exercise, and body mass index (BMI) among adolescent athletes. DESIGN: Cross-sectional study. SETTING: University hospital pediatric sports medicine center. PARTICIPANTS: Sixty-four participants (61% female) of ages 13 to 18 years, actively participating in at least 1 organized sport. MAIN INDEPENDENT VARIABLE: Participant sex. MAIN OUTCOME MEASURES: Average 7-day EA (kcal/kg FFM/d
calculated using participant-recorded dietary intake and exercise expenditure from a wrist-worn heart rate/activity monitor), Eating Disorder Examination Questionnaire (EDE-Q) score (range 0-6), Compulsive Exercise Test (CET) score (range 0-25), and age- and sex-adjusted BMI percentile. RESULTS: There were no significant sex differences in EA (females: 40.37 ± 12.17 kcal/kg FFM/d
males: 35.99 ± 12.43 kcal/kg FFM/d
P = 0.29), EDE-Q (females: 0.68 ± 0.70
males: 0.68 ± 0.83
P = 0.99), or CET scores (females: 11.07 ± 0.44
males: 10.73 ± 0.63
P = 0.66). There were low and insignificant negative correlations between EA and EDE-Q and CET scores for female athletes (EDE-Q: r = -0.22, P = 0.18
CET: r = -0.21, P = 0.09) and male athletes (EDE-Q: r = -0.09, P = 0.66
CET: r = -0.35, P = 0.08). EA and BMI-for-age percentile were inversely correlated in both male (r = -0.451, P = 0.009) and female (r = -0.37, P = 0.02) participants. CONCLUSIONS: In our sample of adolescent athletes, lower EA occurred in the absence of notable disordered eating or compulsive exercise behaviors, suggesting unintentional underfueling (and/or underreporting of energy intake), without significant sex differences. Low BMI can be an imperfect surrogate marker for low EA. These findings inform risk factors and screening practices for low EA among adolescent athletes.