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Breast CancerNCT06399276

4:3 Intermittent Fasting Intervention in Adults With Breast Cancer and Overweight or Obesity

A study testing Weight Loss in people with Breast Cancer, run by University of Colorado, Denver at 2 sites in United States.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This is a 3 month single arm pilot and feasibility study designed to examine the impact of an intermittent fasting lifestyle weight loss intervention on pre-specified clinical milestones (change in body weight, adherence to the fasting program, and moderate-to vigorous physical activity, MVPA) in adults with… Read more about this study

Who is it for?
Ages 18 to 65 years
Conditions the study is for
Breast Cancer
What is being tested?
Weight Loss
Could I receive a placebo?
No, everyone receives an active treatment
How many people
36 participants
Where
2 sitesUnited States
Study dates
28 May 2024to 1 Jun 2027
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 65 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

None listed.

Who cannot join

  • Eastern Cooperative Oncology Group (ECOG) Performance Status 2 or higher.
  • Actively undergoing chemotherapy, radiation, immunotherapy and/or targeted therapy (other than anti-endocrine therapy) or are within 1 month of completion of chemotherapy, radiation, immunotherapy and/or targeted therapy (other than anti-endocrine therapy) as of the target intervention start date. Exceptions to this 1-month timeframe can be made on a case-by-case basis at the discretion of the PI if patients are tolerating therapy without adverse effects and will have completed treatment prior to the intervention start date.
  • Plans to relocate within the next 12 months.
  • Plans for extended travel (>2 weeks) within the next 12 months.
  • Major surgery within the past 3 months (including mastectomy or breast reconstruction but not including lumpectomy or other minor surgeries) or planned major surgery (including mastectomy or breast reconstruction) during the timeframe of the 6 month study intervention and follow-up phases.
  • For Females:
Show all 30Show fewer
  • Currently pregnant or lactating.
  • Pregnant within the past 6 months.
  • Planning to become pregnant in the next 12 months; sexually active women of childbearing potential may be enrolled if they have had a tubal ligation or use a reliable means of contraception.
  • Recent (past 6 months) acute coronary event, unstable angina, coronary revascularization, stroke, pulmonary embolism, or hospitalization for heart failure or cardiac arrythmia.
  • Symptoms suggestive of cardiovascular disease or unstable angina (e.g., chest pain, shortness of breath at rest or with mild exertion, lightheadedness, syncope).
  • Uncontrolled hypertension, defined as diastolic blood pressure >100 mmHG, systolic blood pressure >160 mmHG, or resting heart rate >100 bpm as measured in duplicate on the screening visit after 5 minutes of rest in a seated position.
  • Diabetes (history of type 1 or type 2 diabetes or fasting glucose ≥126 mg/dL or Hemoglobin A1C ≥6.5% as measured on screening labs) unless on metformin or on dipeptidyl peptidase IV (DPP-IV) inhibitor monotherapy and well-controlled with Hemoglobin A1C <8%.
  • Undiagnosed hypo- or hyper-thyroidism (TSH outside of the normal range as measured on screening labs) or history of uncontrolled thyroid disorder. History of thyroid disease or current thyroid disease treated with a stable medication regimen is acceptable.
  • Stage 4 or 5 chronic kidney disease as assessed by estimated glomerular filtration rate <30 as measured on screening labs.
  • Triglycerides >500 mg/dL or LDL cholesterol >200 mg/dL as measured on screening labs.
  • Serious arrhythmias, including multifocal PVC's, frequent PVC's (defined as 10 or more per min), ventricular tachycardia (defined as runs of 3 or more successive PVC's), or sustained atrial tachyarrhythmia; 2nd or 3rd degree A-V block, known QTc interval > 480 msec or other significant conduction defects.
  • Clinically significant abnormalities in hematocrit/hemoglobin, white blood cell count, platelets, serum sodium, potassium, or bicarbonate as measured on screening labs or presence or history of other metabolic or chronic health problems which would impact ability to safely participate in a weight loss intervention involving an intermittent energy restricted diet and exercise including significant cardiac valvular disease or heart failure, significant gastrointestinal, pulmonary, renal, musculoskeletal, neurologic, hematologic, orthopedic, or psychiatric disease.
  • Sustained use of prescription or over-the-counter medications known to significantly impact appetite, weight, or energy metabolism (e.g., anti-obesity pharmacotherapy, appetite suppressants, lithium, stimulants, anti-psychotics, tricyclic antidepressants) with the exception of anti-endocrine directed treatment for breast cancer and standard of care anti-emetic or anti-diarrheal agents.
  • Sustained use of systemic glucocorticoids (current or in the past 6 months) unless physiologic replacement therapy for adrenal insufficiency.
  • Previous obesity treatment with metabolic bariatric surgery or weight loss device, except: (1) liposuction and/or abdominoplasty if performed > 1 year before screening, (2) lap banding if the band has been removed > 1 year before screening, (3) intragastric balloon if the balloon has been removed > 1 year before screening (4) duodenal-jejunal bypass sleeve, if the sleeve has been removed > 1 year before screening or 5) AspireAssist or other endoscopically placed weight loss device if the device has been removed > 1 year before screening.
  • Nicotine use (current or past 6 months)
  • Current alcohol or substance abuse.
  • History of clinically diagnosed eating disorders including anorexia nervosa, bulimia, binge eating disorder. Score >20 on the Eating Attitudes Test (EATS-26) or pattern of response on the Questionnaire of Eating and Weight Patterns (QEWP-5) suggestive of possible binge eating disorder or bulimia will require further assessment by the Study MD to determine if it is appropriate for the subject to participate in the study.
  • Current severe depression or history of severe depression within the previous year, based on DSM-IV-TR criteria for Major Depressive Episode or history of other significant psychiatric illness (e.g., psychosis, schizophrenia, mania, bipolar disorder) which in the opinion of the Study PI would interfere with ability to participate in the diet and exercise interventions and provide feedback on the interventions via questionnaires and focus groups.
  • Currently participating in or planning to participate in any formal weight loss or physical activity programs or clinical trials over the next 12 months.
  • Previous participation (within the past 3 years) in the Anschutz Health and Wellness Center (AHWC) BfitBwell Oncology Exercise Program (exceptions may be made at the discretion of the study PI).
  • Previous participation (within the past 3 years) in a weight loss, exercise, or nutrition research study (exceptions may be made at the discretion of the study PI).
  • Children (individuals under the age of 18 years per NIH guidelines) will not be recruited for the current studies because breast cancer is rare in children and because the lifestyle weight management curriculum used in the study was not designed for children or adolescents.
  • We have elected to exclude adults over the age of 65 years as weight loss may not be advisable in older patients undergoing treatment for breast cancer or in routine follow-up for breast cancer due to issues with loss of lean mass and decreases in functional capacity that can occur with weight loss in older individuals. A separate study on the impact of a lifestyle weight loss intervention in older patients with breast cancer is warranted.

Trial locations and contacts

2 sites in 1 country.

United States2 sites

  • Anschutz Health and Wellness

    Aurora, Colorado, 80045

  • University of Colorado Anschutz Medical Campus

    Aurora, Colorado, 80045

Other trials in United States

About this study

Official title: A Proof-of-Concept Study Evaluating a 4:3 Intermittent Fasting Weight Loss Intervention in Adults With Breast Cancer and Overweight or Obesity

This is a 3 month single arm pilot and feasibility study designed to examine the impact of an intermittent fasting lifestyle weight loss intervention on pre-specified clinical milestones (change in body weight, adherence to the fasting program, and moderate-to vigorous physical activity, MVPA) in adults with overweight and obesity and breast cancer after they have completed their cancer treatment. The investigators will also evaluate feasibility of recruitment and retention of study participants, safety of the intervention, and obtain feedback from participants to improve the program. Participants will receive a 3 month lifestyle weight loss program focusing on a 4:3 intermittent fasting paradigm (3 modified fast days per week) and support to increase physical activity to 150 minutes per week. Outcome measures will be assessed at the end of the 3 month intervention (primary endpoint) and after a 3 month weight maintenance follow up phase.

Conditions
Breast Cancer
Being tested
Weight Loss
Keywords
Overweight, Obese
Medical subject headings
Breast Neoplasms, Overweight, Obesity

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Weight LossBehavioural

    Participants are instructed to perform a modified fast (~500 kcal) on 3 days/week with ad libitum intake the other 4 days/week. Group-based behavioral support sessions will be held by an experienced Registered Dietician. Participants will attend BfitBwell exercise sessions in person and virtually to receive individualized support to progress to 150 min/wk of moderate-intensity physical activity

Study groups in NCT06399276
Study groupRoleWhat they receive
Behavioral Weight Loss Focused on Intermittent FastingExperimental3-month integrated behavioral weight loss intervention with a dietary focus on intermittent fasting.
Receives: Behavioral: Weight Loss

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Body Weight

    Measured using digital scale accurate to =/-0.1 kg, in the morning in a fasted state

    Measured: 3 months

  2. Adherence to 4:3 Intermittent Fasting Dietary Paradigm as Measured by Food Records

    Dietary energy intake assessed using written food records for 7 consecutive days

    Measured: 3 months

  3. Physical Activity

    Moderate to Vigorous Physical Activity (MVPA) (min/wk) measured with the activPALv4 activity monitor for 7 consecutive days.

    Measured: 3 months

Secondary outcomes (2)

  1. Rate of Enrollment

    Number of participants enrolled per month during the recruitment phase.

    Measured: at recruitment

  2. Percent of Participants Completing Outcome Measures

    Retention of participants in the 3-month intervention assessed by percent of enrolled participants that complete outcome measures.

    Measured: 3 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted3 May 2024
  2. Study start28 May 2024
  3. Primary completion30 Apr 2026
  4. Study completion1 Jun 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Supportive care
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
36 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06399276
Sponsor's protocol ID
23-1546.cc
Other IDs
R01CA258766
Status last verified
Aug 2026
First submitted
30 Apr 2024
Last updated
1 Sep 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Publications

  • Oselinsky KM, Hill EB, Ostendorf DM, Pan Z, Bing K, Wayland LT, Simpson C, Clark KC, Sandoval A, Thomas EA, Marker RJ, Kabos P, MacLean PS, Catenacci VA. Exploring the Feasibility, Acceptability, and Safety of a 4:3 Intermittent Fasting Weight Loss Program Among Stage I-III Breast Cancer Survivors With Overweight or Obesity: Protocol for a 6-Month Proof-of-Concept Feasibility Trial. JMIR Res Protoc. 2026 Jul 23;15:e86281. doi: 10.2196/86281.

    PubMed 42492498

Questions about this trial

What is this clinical trial studying?

A study testing Weight Loss in people with Breast Cancer, run by University of Colorado, Denver at 2 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 0 inclusion and 30 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 1 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Body Weight (time frame: 3 months). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06399276, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 1 Sep 2026.

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