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Protocol Details

CaREFREE Study (Calorie Restriction, Environment and Fitness: Reproductive Effects Evaluation Study)

This study is NOT currently recruiting participants.

Summary | Eligibility | Citations | Contacts




Sponsoring Institute

National Institute of Environmental Health Sciences (NIEHS)

Recruitment Detail

Type: Completed Study; data analyses ongoing
Gender: Female
Min Age: 18 Years
Max Age: 28 Years

Referral Letter Required


Population Exclusion(s)

Non-English Speaking;


Luteinizing Hormone (LH);
Weight Loss;
Functional Hypothalamic Amenorrhea (HA);
Gonadotropin-Releasing Hormone (GnRH);
Energy Deficiency

Recruitment Keyword(s)




Investigational Drug(s)


Investigational Device(s)



Behavioral: NEA
Behavioral: DEA

Supporting Site

National Institute of Environmental Health Sciences


Functional hypothalamic amenorrhea (functional HA) is a condition where a woman s period stops for a temporary time. This is due to improper function of the hypothalamus. This is the part of the brain that directs the whole reproductive system. Researchers want to learn more about functional HA. They also want to learn how diet, exercise, and other factors may change women s menstrual cycles.


To better understand functional HA.


Healthy women ages 18-28 years old who:

-Have regular periods

-Exercise no more than 4 hours a week

-Had their first period at age 11-14


Participants will be prescreened over the phone.

Participants will be screened with:

-Blood and urine tests

-Medical history

-Physical exam.

Participants will have 9 or 10 visits over about 3 menstrual cycles. These include:

-Repeat of screening tests


-Exercise test

-Resting energy expenditure test: Participants fast overnight before the test. They lie on their back under a canopy for a half hour.

-Body composition test: This is done with a dual energy x-ray absorptiometry (DXA) scan.

-Pelvic ultrasound

-For two full-day visits, an IV is inserted into an arm vein. The IV takes a blood sample every 10 minutes for 8 hours.

Participants will keep logs:

-Menstrual cycle log

-Diet log for three 4-day cycles

Participants will receive test kits to complete at home:

-Daily blood and urine sample


Participants will take a daily iron supplement. They will wear a wristband that monitors activity 24 hours a day.

Participants will stick to a special diet for two 5-day periods of time. They will complete two 4-day exercise programs.

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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 less than or equal to 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 (Summation)m(2) and a weight >= 93 lbs.

7. Agrees to use barrier contraception method for the duration of the study

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. Is willing and able to fulfill the requirements of the protocol and to provide informed consent

11. Able to speak and read English

12. Lives within 50 miles of the Clinical Research Unit


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 lbs)

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:


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 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. History of thyroid disorder is permissible if the patient is biochemically euthyroid on replacement.

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 less than or equal to 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

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Loucks AB. The response of luteinizing hormone pulsatility to 5 days of low energy availability disappears by 14 years of gynecological age. J Clin Endocrinol Metab. 2006 Aug;91(8):3158-64. Epub 2006 May 23.

Loucks AB, Thuma JR. Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. J Clin Endocrinol Metab. 2003 Jan;88(1):297-311.

Williams NI, Young JC, McArthur JW, Bullen B, Skrinar GS, Turnbull B. Strenuous exercise with caloric restriction: effect on luteinizing hormone secretion. Med Sci Sports Exerc. 1995 Oct;27(10):1390-8.

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Principal Investigator

Referral Contact

For more information:

Janet E. Hall, M.D.
National Institute of Environmental Health Sciences (NIEHS)
(984) 287-3647

NIEHS Join A Study Recruitment Group
National Institute of Environmental Health Sciences (NIEHS)

(855) 696-4347

Lisa B. Barber, MEd
Building 109 - Modular Clinic, 121
111 T W Alexander Dr
Research Triangle Prk, NC, 27709
(984) 287-4410

Clinical Trials Number:


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