Bone mineral density and estimated hip strength in men with anorexia nervosa, atypical anorexia nervosa and avoidant/restrictive food intake disorder

Objective: Few bone mineral density (BMD) data are available in men with anorexia nervosa (AN), and none in those with atypical AN (ATYP) (AN psychological symptoms without low weight) or avoidant/restrictive food intake disorder (ARFID) (restrictive eating without AN psychological symptoms). We investigated the prevalence and determinants of low BMD and estimated hip strength in men with these disorders. Design: Cross-sectional: two centres. Patients: A total of 103 men, 18-63 years: AN (n = 26), ARFID (n = 11), ATYP (n = 18), healthy controls (HC) (n = 48). Measurements: Body composition, BMD and estimated hip strength (section modulus and buckling ratio) by DXA (Hologic). Serum 25OH vitamin D was quantified, as was daily calcium intake in a subset of subjects. Results: Mean BMI was lowest in AN and ARFID, higher in ATYP and highest in HC (AN 14.7 ± 1.8, ARFID 15.3 ± 1.5, ATYP 20.6 ± 2.0, HC 23.7 ± 3.3 kg/m²) (P < 0.0005). Mean BMD Z-scores at spine and hip were lower in AN and ARFID, but not ATYP, than HC (postero-anterior (PA) spine AN −2.05 ± 1.58, ARFID −1.33 ± 1.21, ATYP −0.59 ± 1.77, HC −0.12 ± 1.17) (P < 0.05). 65% AN, 18% ARFID, 33% ATYP and 6% HC had BMD Z-scores <−2 at ≥1 site (AN and ATYP vs HC, P < 0.01). Mean section modulus Z-scores were lower in AN than HC (P < 0.01). Lower BMI, muscle mass and vitamin D levels (R = 0.33-0.64), as well as longer disease duration (R = −0.51 to −0.58), were associated with lower BMD (P < 0.05). Conclusions: Men with AN, ARFID and ATYP are at risk for low BMD. Men with these eating disorders who are low weight, or who have low muscle mass, long illness duration and/or vitamin D deficiency, may be at particularly high risk.