Study reveals how cutting calories disrupts Women's periods

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

* INCLUSION CRITERIA: Participants will be enrolled with distribution across race. Each potential participant must meet all of the following inclusion criteria in order to be eligible to enroll in the study: 1. Female 2. Between 18 and 28 years of age (inclusive) 3. Reported menarche between the ages of 11 and 14 years 4. Gynecological age of \<= 14 years 5. A history of self-reported regular menstrual cycles when not on contraceptive medication of between 25 and 35 days (inclusive) at prescreen and knowledge of date of onset of menses before the screening visit 6. A BMI of 18.5 to 27 kg x m\^2 and a weight \>= 93 lbs. 7. Agrees to use barrier contraception method for the duration of the study and the follow up period 8. Agrees to abstain from alcohol consumption during both 5-day diet/exercise study interventions 9. Agrees to abstain from donating blood during the study and within 30 days of completing the study 10. Agrees to abstain from biotin supplements for the duration of the study 11. Is willing and able to fulfill the requirements of the protocol and to provide informed consent 12. Able to speak and read English 13. Lives within 50 miles of the Clinical Research Unit EXCLUSION CRITERIA: A potential participant meeting any of the following exclusion criteria is not eligible to enroll in the study: 1. Currently lactating or pregnant or planning on becoming pregnant for the duration of the study 2. Has ever given birth 3. History in the past 3 months of dieting or weight loss amounting to greater than 2 kg 4. \> 4 hours per week of aerobic exercise for the past 3 months 5. Has initiated training for an athletic sport or event in the past 3 months that, in the opinion of the investigator, may interfere with the results of the study 6. Currently using hormone-based contraception, including those administered orally, vaginally, via injection, sub-dermally, or transdermally 7. Current use of medications or supplements that may interfere with the results of the study, including: i.Steroids ii.Hormone-based contraception iii.Sleeping pills iv.Homeopathic substances (e.g. Chinese herbs, protein or other powders, and other-the-counter extracts) v.Stimulants (e.g. Ritalin) vi.Antidepressants or anti-epileptic medications or centrally acting anti-hypertensive medications 8. Current use of recreational drugs (alcohol intake will be monitored and excluded during the two intervention periods) 9. Unable to consume food containing dairy or nuts 10. Has regular overnight awake periods, for example overnight or rotating shift work, that will continue during the study, at the discretion of the investigator 11. Has currently or has a history of any of the following: autoimmune, heart, liver, renal disease, diabetes, or another health condition deemed by the PI to be a contraindication to study participation. Additional Eligibility Criteria to be Met Prior to Start of Intervention(s): Criteria 1 Habitual energy intake between 35-55 kcal/kg LBM\*day Criteria 2 VO2max \<= 40 ml/kg/min with the option to increase this at the discretion of the PI, depending on the current and past exercise level of the participant. Criteria 3 Hemoglobin, prolactin and TSH within normal female range for testing laboratory. Criteria 4 Ovulation confirmed in the cycle before each study intervention by self-reported positive urine test, ultrasound and/or progesterone blood-levels