Both low energy availability and estrogen deficiency are detrimental to bone, but the significance of each independently are not abundantly understood, as energy and estrogen deficiency often occur simultaneously. Using data from a Randomized Control Trial, REFUEL, we further examined the relationship between estrogen, energy and bone turnover. Based on our findings, energy status was a better predictor and had greater influence on the components of bone turnover and bone turnover rate than estrogen status.