Purpose: To determine the energetic and hormonal predictors of advanced menstrual recovery (>=2 consecutive menstrual cycles of <36 d) in the REFUEL study, a 12-month intervention of increased energy intake in exercising women with oligo/amenorrhea. Methods: Participants (21.8 ± 0.7 yr; N = 25) were categorized based on whether they experienced advanced menstrual recovery (REC) or not (non-REC). Potential recovery predictors were measured at baseline (BL) and at the time point preceding advanced menstrual recovery (PRE). For the non-REC group, PRE was the measurement preceding the last two menstrual cycles/28-d amenorrheic monitoring periods recorded during the intervention. Predictors included body composition, energy intake, energy availability, urinary estrone-1-glucuronide and pregnanediol glucuronide, serum metabolic hormones, and resting metabolic rate variables. T tests and Mann-Whitney U tests assessed group differences. Logistic regressions determined recovery predictors. Results: The REC group had higher percent fat (25.7 ± 1.0% vs 21.8 ± 1.0%, P = 0.006) and fat mass (14.7 ± 0.7 vs 11.6 ± 0.7 kg, P = 0.003) at BL and fat mass (15.3 ± 0.6 vs 13.4 ± 0.5 kg, P = 0.019), insulin-like growth factor-1 (273.1 ± 13.5 vs 229.6 ± 19.3 ng·mL-1, P = 0.036), and leptin (7.5 ± 1.3 vs 4.6 ± 0.7 ng·mL-1, P = 0.033) at PRE than the non-REC group. Estrone-1-glucuronide and pregnanediol glucuronide increased in the REC group (from 27.6 ± 4.5 to 35.3 ± 5.0 ng·mL-1, P = 0.007; from 1.2 ± 0.2 to 1.3 ± 0.2 µg·mL-1, P < 0.001). Predictors of menstrual recovery were the number of menstrual cycles experienced in the 12 month before the intervention, BL percent fat and fat mass, and fat mass and insulin-like growth factor-1 at PRE (P < 0.05). Combining BL fat mass and previous 12-month menstrual frequency correctly classified 91.3% of women as REC or non-REC. Conclusions: A higher fat mass and a previous pattern (12-month) of frequency of menses may have an important role for advanced menstrual recovery to be achieved.
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