Our objective was to investigate how bone metabolism change through body weight gain in women with anorexia nervosa (AN).

This retrospective research at one hospital included 36 women with AN (mean age±SEM, 30±11.3 years, mean BMI±SEM 12.1±1.2kg/m²) treated with our CBT program. We measured their bone mineral density (BMD) of the spine and whole body by dual-energy x-ray absorptiometry, serum intact N-terminal propeptide of type 1 procollagen (P1NP), tartrate-resistant acid phosphatase-5b (TRACP-5b) and sclerostin before and after the treatment.

At baseline, BMD negatively correlated with amenorrhea duration. Upon completion, the body weight increased 8.8±2.9kg. But they all remained amenorrhea. BMD significantly decreased (posteroanterior spine, –2.7±1.3%; whole body, –1.7±0.5%). Serum intact P1NP levels increased (p<0.001) and TRACP-5b levels decreased (p=.006), whereas sclerostin levels were stable (p=.3) over this treatment. Change in BMD did not correlate with intact P1NP and TRACP-5b levels. However, there was a significant association between change in sclerotin levels and percent change in PA spine BMD (r=0.45, p=.008). There was an inverse relationship between baseline serum sclerostin levels and percent change in whole body BMD (r=–0.54; p=.001).

This study demonstrates that weight gain induces bone formation and reduces bone resorption in women with severe AN regardless of BMD change. Levels of sclerostin at baseline could be a good predictor of reaction of BMD.