Clinical Research Directory

Inclusion Criteria: 1. Female 2. Age 18-25 yrs 3. BMI 18-29 kg/m2 4. Non-smoking 5. Willing to refrain from using hormonal contraceptives for the equilibration + baseline period of the study (\~150 days) 6. Availability to frequently visit the laboratory in the next 12 months 7. Not currently pregnant nor intending to become pregnant in the next 12 months 8. Not lactating 9. No apparent metabolic, endocrine, musculoskeletal, or severe psychiatric disease 10. Willing to maintain consistent exercise (aerobic, weight-bearing) and dietary habits during pre-intervention and intervention periods 11. Willing to refrain from supplements other than those provided by study staff in the next 12 months 12. Variable physical activity acceptable, but mode must be primarily weight bearing 13. At least 9 menses in the past 12 months Exclusion Criteria: 1. Non-weight bearing exercise as primary mode of physical activity 2. Resistance exercise training (≥ 2 times 30 minutes per week of resistance exercise) 3. Complete seasonal change of impact mode of physical activity 4. Known or suspected metabolic or endocrine disease 5. Smoking 6. Pregnant 7. Currently consuming large amounts of soy products 8. Current clinical eating disorder or other axis 1 psychiatric disorder or bipolar disorders 9. Oral or hormonal contraceptive use in the last 6 months 10. Hyperparathyroidism 11. Liver or renal disease 12. Evidence of malabsorption or skeletal disorder 13. Thyroid abnormalities (controlled hypothyroidism acceptable) 14. Chronic use of non-steroidal anti-inflammatory drugs (NSAIDS) 15. Taking medications known to have interactions with oral or vaginal contraceptive therapy 16. Other Exclusion Criteria proposed by the World Health Organization COC Contraindications (Grossman et al., 2011).