Mild dieting may alter birth control hormone levels, study suggests
NCT ID NCT07651800
First seen Jun 25, 2026 · Last updated Jun 27, 2026 · Updated 2 times
Summary
This study looks at how a modest daily calorie deficit of about 250 calories affects reproductive hormones like estrogen and progesterone in women using different types of birth control (oral pills, hormonal IUD, or non-hormonal IUD). Researchers will track 30 recreationally active women aged 18-35 over two menstrual cycles—one normal and one with the calorie deficit. The goal is to see if mild energy restriction changes hormone exposure, which could have implications for contraceptive effectiveness and overall health.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- What this could lead to
- If successful, this study could help understand how mild calorie restriction interacts with hormonal contraceptives, potentially informing future guidelines for active women.
- What could go wrong
- This is a small, early-stage observational study with only 30 participants, so results may not apply broadly. It does not test a treatment or intervention.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
-
About 30 people
The number the study aims to enrol. It can still change while the study runs.
- Expected to start
-
Sep 2026
An estimate. Start dates often move.
- Expected to finish
-
Dec 2027
An estimate. End dates often move.
- Lead sponsor
-
Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
-
18 to 35 years
- Sex
-
Female participants only
- Healthy volunteers
-
Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: * Female, aged 18-35 years * Recreationally active (engaging in structured exercise between 8-15 hours per week) * BMI of 18.5-29.9 as a BMI below or above these cut points results in highly varied menstrual cycle lengths17 * Not currently experiencing an eating disorder or disordered eating, or having a diagnosed eating disorder in the last 3 years * Non-pregnant or planning to become pregnant * Medically free from chronic diseases * Currently using one of the following contraceptive methods for ≥3 months: Monophasic oral contraceptive * Hormonal intrauterine device (H-IUD) * Copper intrauterine device * Weight stable (no weight change \>5% body weight within the past 3 months) * Weight greater than or equal to 110 lbs * Not suffering from known gynecological disease (i.e., PCOS, endometriosis, etc.) that may influence menstrual cycle regularity * Willing and able to maintain current exercise habits throughout the study * Willing to follow study dietary guidance to achieve a \~250 kcal/day energy deficit during Cycle 2 Exclusion Criteria: * Amenorrhea or oligomenorrhea * Perimenopausal or menopausal * Currently pregnant, planning pregnancy, or breastfeeding * Use of hormonal contraception other than monophasic oral contraceptives or hormonal IUD (implant, nuvaring, etc.) * Initiation or change of contraceptive method within the past 3 months * Diagnosis of polycystic ovary syndrome (PCOS), endometriosis, hypothalamic amenorrhea, or other known reproductive endocrine disorder * Current or history of eating disorder or clinically diagnosed disordered eating * Current participation in intentional weight loss or weight gain program * Use of medications known to affect metabolism or hormone levels (e.g., systemic corticosteroids, thyroid medications, insulin, GLP-1 agonists) * Known metabolic, cardiovascular, renal, hepatic, or endocrine disease * Musculoskeletal injury limiting exercise participation within the past 3 months * Smoking or nicotine use * Contraindications to DXA scanning (e.g., pregnancy, recent high-radiation diagnostic imaging exceeding institutional limits) * Inability or unwillingness to comply with study procedures
Get updates
Get notified about this study
Sign up to get updates when this study changes or when new studies for Energy deficiency due to short-term fasting are added.
Genom att skicka in godkänner du våra Användarvillkor
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
-
The places running it
1 site. The list below names each one and where it is.
-
The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
-
A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
-
University of Southern California Health Sciences Campus Center for Health Professions
Los Angeles, California, 90033, United States
More trials for these conditions
Other studies related to the condition(s) this trial covers.