Exploratory Study Therapeutic Fasting Reduce Physical Limitations, Quality of Life During Aromatase Inhibitor Therapy (FREE-AI)

Exploratory Study of Therapeutic Fasting to Reduce Limitations in Physical Well-being and Quality of Life During Endocrine Therapy With Aromatase Inhibitors

In this explorative study, the feasibility of therapeutic fasting to reduce limitations in physical well-being and quality of life of patients undergoing endocrine therapy with aromatase inhibitors will be investigated. In addition, the application of the StudyU app, which is currently under development, will be monitored and the app adapted if necessary. In addition, in preparation for a larger multicenter main study, it will be examined whether the muscle and joint complaints frequently experienced by patients undergoing endocrine therapy with aromatase inhibitors (AI) can be alleviated by a 7-day guided therapeutic fasting intervention (prolonged fasting / PF) can be improved.

Study Overview

• Status: Completed
• Conditions: Breast Cancer Patients Treated With Aromatase Inhibitors
• Intervention / Treatment: Other: Fasting

Detailed Description

After baseline (t0), all patients will receive the following intervention:

7 days of online supervised prolonged therapeutic fasting (max. 350 kcal/d).

Following the study intervention, at t1, patients will be offered a for a potential effect as sustainable as possible in addition to a dietary change.

According to the following criteria:

• As plant-based as possible
• Rich in nutritive prebiotics
• In addition, this group should include intermittent fasting/time restricted eating (16/8h) into their dietary habits (at least 6d/week).

All patients will be interviewed on a regular basis and anthropometric data will be collected accordingly at following time points:

• t1 (at the end of the fasting intervention).
• t2 (3 months after t0)

• Study Type: Interventional
• Enrollment (Actual): 54
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Germany
  • Baden Würtenberg
    • Stuttgart, Baden Würtenberg, Germany, 70341
      • Robert-Bosch-Krankenhaus
  • Bavaria
    • Würzburg, Bavaria, Germany, 97080
      • Würzburg University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients with curatively treated hormone receptor positive breast cancer who have been on aromatase inhibitors (AI) therapy for at least 3 months and have significant Pain (NRS>4).
• Informed consent.

Exclusion Criteria:

• Eating disorders.
• Permanent medication other than endocrine therapy, which would constitute an absolute or relative contraindication to outpatient fasting, such as Marcumar, lithium, Antiepileptic drugs, etc.
• Patients with diabetes mellitus type 1 or 2
• Uncontrolled cerebral seizure disorder.
• Participation in another diet/fasting study.
• Lack of willingness to store and share personal medical data within the framework of the protocol.
• Insufficient knowledge of the German language.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Therapeutic fasting for the reduction of physical of limitations in physical well-being and qol	Other: Fasting; Sieben days of online supervised prolonged therapeutic fasting (max. 350 kcal/d).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Numerical rating scale	The numerical rating scale (NRS) will be used to assess the intensity of pain on a range of 0 to 10, with 0 as no pain and 10 as the most intense pain.	After 7 days (end of intervention)
Brief Pain Inventory	The Brief Pain Inventory (BPI) scale will measure how pain has interfered with activities of daily living (general activity, walking, work, mood, enjoyment of life, relationships with others and sleep). Pain score: 1 - 4: Mild pain, 5 - 6: Moderate pain and 7 - 10: Severe pain.	After 7 days (end of intervention)
Fibromyalgia Impact Questionnaire	The Fibromyalgia Impact Questionnaire (FIQ) has 10 items measuring physical functioning, mood, depression, anxiety, sleep, pain, stiffness, fatigue and well-being. Each item has a maximum score of 10 points, so the overall maximum score is 100.	After 7 days (end of intervention)
Health Assessment Questionnaire-Diasbility Index	The Health Assessment Questionnaire-Diasbility Index (HAQ-DI) will be applied to assess the daily activity of patients, consists of 20 questions and is scored from 0 (no disability) to 3 (total disability).	After 7 days (end of intervention)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
World Health Organization's 5	The WHO-5 questionnaire will be used to assess the subjective mental well-being of patients. Each question is scored from 0 to 5. Low scores correspond to low level of well-being.	After 7 days (end of intervention)
World Health Organization's 5	The WHO-5 questionnaire will be used to assess the subjective mental well-being of patients. Each question is scored from 0 to 5. Low scores correspond to low level of well-being.	Follow-up 3 Moths after the baseline.
Mindfulness and Awareness Scale	The Mindfulness and Awareness Scale (MAAS) measures a person's level of mindfulness in daily life. It evaluates how much time an individual spends in the present time. The scale ranges from 1 to 6 and consists of 15 items in total.	After 7 days (end of intervention)
Mindfulness and Awareness Scale	The Mindfulness and Awareness Scale (MAAS) measures a person's level of mindfulness in daily life. It evaluates how much time an individual spends in the present time. The scale ranges from 1 to 6 and consists of 15 items in total.	Follow-up 3 Moths after the baseline.
Relief of Cancer-related-Fatigue	The Relief of Cancer-related-Fatigue (BFI) is used to quickly assess the severity and impact of cancer-related fatigue. The questionnaire consists of 10 items covering six dimensions: Activity, mood, walking ability, work, relationship with others, and enjoyment of life. A score between 30 and 40 indicates moderate fatigue, scores above 70 indicate severe fatigue.	After 7 days (end of intervention)
Relief of Cancer-related-Fatigue	The Relief of Cancer-related-Fatigue (BFI) is used to quickly assess the severity and impact of cancer-related fatigue. The questionnaire consists of 10 items covering six dimensions: Activity, mood, walking ability, work, relationship with others, and enjoyment of life. A score between 30 and 40 indicates moderate fatigue, scores above 70 indicate severe fatigue.	Follow-up 3 Moths after the baseline.
Pittsburgh Sleep Quality Index	The Pittsburgh Sleep Quality Index (PSQI) measures subjective sleep quality. The questionnaire consists of 19 items and 7 component scores are obtained, each of which is scored from 0 (no difficulty) to 3 (severe difficulty). The component scores are summed to produce a global score (range 0 to 21). Higher scores indicate worse sleep quality.	After 7 days (end of intervention)
Pittsburgh Sleep Quality Index	The Pittsburgh Sleep Quality Index (PSQI) measures subjective sleep quality. The questionnaire consists of 19 items and 7 component scores are obtained, each of which is scored from 0 (no difficulty) to 3 (severe difficulty). The component scores are summed to produce a global score (range 0 to 21). Higher scores indicate worse sleep quality.	Follow-up 3 Moths after the baseline.
Blood pressure	It is defined as the force exerted by the blood on the arterial walls to circulate through the arteries and is measured in mm Hg. A normal value is considered to be less than 120/80 mmHg.	After 7 days (end of intervention)
Blood pressure	It is defined as the force exerted by the blood on the arterial walls to circulate through the arteries and is measured in mm Hg. A normal value is considered to be less than 120/80 mmHg.	Follow-up 3 Moths after the baseline.
Heart rate	It is defined as the number of times the heart pumps blood during a minute and is measured as the number of beats per minute. Between 60 and 100 beats per minute is considered a normal value.	After 7 days (end of intervention)
Heart rate	It is defined as the number of times the heart pumps blood during a minute and is measured as the number of beats per minute. Between 60 and 100 beats per minute is considered a normal value.	Follow-up 3 Moths after the baseline.
Food habits	A standardized questionnaire will be used, where the following will be recorded: eating habits.	Follow-up 3 Moths after the baseline.
Body-Mass-Index	Body-Mass-Index (BMI) is a measure of body weight classification and is calculated based on weight and height, with the unit of measurement kg/m2. A BMI between 18.5 and 24.9 is considered normal weight, between 25 and 29.9 is defined as slightly overweight and a value above 30 is called severely overweight (obesity).	After 7 days (end of intervention)
Body-Mass-Index	Body-Mass-Index (BMI) is a measure of body weight classification and is calculated based on weight and height, with the unit of measurement kg/m2. A BMI between 18.5 and 24.9 is considered normal weight, between 25 and 29.9 is defined as slightly overweight and a value above 30 is called severely overweight (obesity).	Follow-up 3 Moths after the baseline.
Abdominal circumference	It is an anthropometric measurement used to establish the fat accumulated in a person in the abdominal area and is measured in centimeters (cm). For women, below 80cm is low risk, 80-88cm is high risk and more than 88cm is very high.	After 7 days (end of intervention)
Abdominal circumference	It is an anthropometric measurement used to establish the fat accumulated in a person in the abdominal area and is measured in centimeters (cm). For women, below 80cm is low risk, 80-88cm is high risk and more than 88cm is very high.	Follow-up 3 Moths after the baseline.
Triglycerides	Type of lipid found in the bloodstream and adipose tissue. Normal values are between 150-199 mg/dl, high between 200-499 mg/dl and very high values above 500 mg/dl.	After 7 days (end of intervention)
Triglycerides	Type of lipid found in the bloodstream and adipose tissue. Normal values are between 150-199 mg/dl, high between 200-499 mg/dl and very high values above 500 mg/dl.	Follow-up 3 Moths after the baseline.
Gamma-Glutamyl-Transferase	This is an enzyme found mainly in the liver. Its normal values are between 5-40 U/L.	After 7 days (end of intervention).
Gamma-Glutamyl-Transferase	This is an enzyme found mainly in the liver. Its normal values are between 5-40 U/L.	Follow-up 3 Moths after the baseline.
Fatty Liver Index	Fatty Liver Index (FLI) is a predictor of hepatic steatosis, calculated from BMI, waist circumference, y-GT and triglycerides.	After 7 days (end of intervention)
Fatty Liver Index	Fatty Liver Index (FLI) is a predictor of hepatic steatosis, calculated from BMI, waist circumference, y-GT and triglycerides.	Follow-up 3 Moths after the baseline.
Adverse events	Adverse events and serious adverse events are documented. Adverse events include any adverse symptoms, illnesses, disorders, or accidents that occur during the course of the study. Serious adverse events include events occurring during the course of the study that are immediately life-threatening and/or result in serious health problems (specifically, requiring unanticipated hospitalization or prolongation of hospitalization, or resulting in serious disability or incapacitation). The severity as well as the possible causal relationship with the intervention will be assessed by the study physician.	After 7 days (end of intervention)
Adverse events	Adverse events and serious adverse events are documented. Adverse events include any adverse symptoms, illnesses, disorders, or accidents that occur during the course of the study. Serious adverse events include events occurring during the course of the study that are immediately life-threatening and/or result in serious health problems (specifically, requiring unanticipated hospitalization or prolongation of hospitalization, or resulting in serious disability or incapacitation). The severity as well as the possible causal relationship with the intervention will be assessed by the study physician.	Follow-up 3 Moths after the baseline.

Collaborators and Investigators

• Sponsor: University Hospital Tuebingen
• Collaborators: Charite University, Berlin, Germany; Robert Bosch Gesellschaft für Medizinische Forschung mbH (RBMF)
• Investigators: Principal Investigator: Claudia Loeffler, Dr, University Hospital Wuerzburg

Publications and helpful links

General Publications

• Meyer H, Koppold DA, Shaker O, Eden L, Schiffmann L, Konigorski S, Cramer H, Choi KA, Einsele H, Winkler M, Loffler C. Therapeutic Fasting as a Novel Approach to Mitigate Musculoskeletal Symptoms in Breast Cancer Patients undergoing Aromatase Inhibitor Therapy: A Feasibility Study Protocol. Integr Cancer Ther. 2026 Jan-Dec;25:15347354261426272. doi: 10.1177/15347354261426272. Epub 2026 Mar 10.

Study record dates

Study Major Dates

• Study Start (Actual): December 15, 2023
• Primary Completion (Actual): December 30, 2024
• Study Completion (Actual): September 30, 2025

Study Registration Dates

• First Submitted: November 2, 2023
• First Submitted That Met QC Criteria: December 14, 2023
• First Posted (Actual): December 15, 2023

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 11, 2026
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: Fasting; Aromatase Inhibitors
• Additional Relevant MeSH Terms: Behavior; Feeding Behavior; Fasting; Angptl4 protein, mouse
• Other Study ID Numbers: S00805-NIM

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No