FastingCoFFIeNCT07691736
Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits
A study testing Fibre Arm in people with Fasting and Dietary Fibre, run by Buchinger Wilhelmi Development & Holding GmbH at 1 site in Germany.
Trial summary
This study builds on the knowledge that fasting provides metabolic health benefits and that prebiotic interventions can enhance the gut microbiome's metabolic output to likewise improve host health. Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Fasting, Dietary Fibre, Gut Microbiome
- What is being tested?
- Fibre Arm
- Type of treatment
- Pill or oral medicine, Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 75 participants
- Where
- 1 siteGermany
- Study dates
- 31 Aug 2026to Mar 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
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Men and women
- Age: 18-65 years old
- Fasting for 10±4 days at the Buchinger Wilhelmi clinic in Überlingen
- BMI ≥ 25 kg/m²
- Signed informed consent
Who cannot join
- intake of antibiotics up to 2 months prior the study
- regular intake of pre-, post- and probiotics up to 2 months prior the study
- diagnosed Crohn's disease, Ulcerative colitis, IBD, coeliac disease
- medicated high blood pressure
- diagnosed diabetes mellitus type I
- medicated diabetes mellitus type II
Show all 13Show fewer
- diagnosed kidney stone
- active malignant disease
- known substance addiction
- pregnancy or breastfeeding
- diagnosed with cachexia, anorexia nervosa, advanced kidney, liver or cerebrovascular insufficiency
- inability to sign the informed consent
- participation in another study
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Germany1 site, 1 recruiting
- Recruiting
Buchinger Wilhelmi Development & Holding
Überlingen, Baden-Wurttemberg, 88662
Elena Katharina Stroppel, 00497551807675, katharina.stroppel@buchinger-wilhelmi.com
forschung@buchinger-wilhelmi.com
About this study
This study builds on the knowledge that fasting provides metabolic health benefits and that prebiotic interventions can enhance the gut microbiome's metabolic output to likewise improve host health. Whether long-term fasting and dietary fibre interventions could be combined to achieve synergistic improvements in host metabolic health is however unknown. The goal is to provide a proof of concept in a human trial that supplementing 10±4 days fasting with dietary fibre synergistically improves metabolic outcomes via gut microbiome-mediated effects. To assess this, we aim to analyse gut microbiome changes, functional outputs, and key metabolic markers such as butyrate production, glycaemic control and ketosis.
The randomised controlled trial includes 75 participants and has two arms: one involving fasting with fibre supplementation (n = 50) and one involving fasting without fibre supplementation (n = 25). All participants will undergo a fasting period of 10±4 days according to the Buchinger Wilhelmi protocol, followed by a stepwise reintroduction of food of up to 4 days. As dietary fibre we will use maize-derived resistant starch type IV, selected based on its ability to stimulate beneficial gut microbes like Oscillibacter and corn starch as placebo. Two main visits will be conducted: before and at the end of the fasting period. During these visits, blood and stool samples will be collected, and questionnaires will be completed. Additionally, daily measurements of anthropometric parameters and well-being will be recorded. Stool samples will also be collected one month afterwards as a follow-up. Participants' metabolic health will be evaluated through various clinical parameters (e.g., body measurements, blood pressure, glycaemic control, ketones, well-being). Additionally, multi-omics data, including metagenomics and metabolomics, will provide insight into the composition of the microbiome, as well as its outputs and functions. Furthermore, the effects of fasting on extracellular vesicles in blood will be explored.
- Conditions
- Fasting, Dietary Fibre, Gut Microbiome, Metabolism Changes, Overweight , Obesity
- Being tested
- Fibre Arm, Control Arm
- Keywords
- long-term fasting, fasting, continuous glucose monitoring, fibre supplementation, gut microbiome, metabolic health, resistant starch IV, metabolomics, ketosis, extracellular vesicles
- Medical subject headings
- Fasting, Overweight, Obesity, Ketosis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Fibre ArmDietary supplement
10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 20 g/day of maize-derived resistant starch type IV.
Control ArmDietary supplement
10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 1.2 g/day of corn starch placebo.
| Study group | Role | What they receive |
|---|---|---|
| Fibre Arm | Active comparator | Participants (n=50) undergo a 10±4-day fasting period according to the Buchinger Wilhelmi fasting programme and receive maize-derived resistant starch type IV at a total dose of 20 g per day. The powder is blended into a carbohydrate-free electrolyte powder, divided into two equal daily doses, diluted in approximately 0.2 litres of water, and taken orally in the morning and at dinnertime throughout the fasting period. The fasting period is followed by a structured food reintroduction period according to the standard procedure of the Buchinger Wilhelmi Clinic. All other aspects of the intervention, including the fasting and nutritional protocol, clinical supervision, and study assessments, are identical to the control arm. Receives: Dietary Supplement: Fibre Arm |
| Control Arm | Placebo comparator | Participants (n=25) undergo a 10±4-day fasting period according to the Buchinger Wilhelmi fasting programme and receive corn starch placebo at a total dose of 1.2 g per day. The powder is blended into a carbohydrate-free electrolyte powder, divided into two equal daily doses, diluted in approximately 0.2 litres of water, and taken orally in the morning and at dinnertime throughout the fasting period. The fasting period is followed by a structured food reintroduction period according to the standard procedure of the Buchinger Wilhelmi Clinic. All other aspects of the intervention, including the fasting and nutritional protocol, clinical supervision, and study assessments, are identical to the intervention arm. Receives: Dietary Supplement: Control Arm |
What is being measured
The primary outcome is the main question the study is designed to answer.
Abundance of butyrate-producing gut bacteria
Change in the relative abundance of butyrate-producing gut bacteria assessed by metagenomic profiling of faecal samples.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in fasting venous plasma glucose
Fasting venous plasma glucose concentration measured by clinical laboratory analysis (mmol/L).
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Secondary outcomes (7)
Change in body weight
Body weight (kg) measured as part of the clinical health assessment.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in body mass index
Body mass index calculated from measured body weight and height (kg/m²).
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in waist circumference
Waist circumference (cm) measured as part of the clinical health assessment.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in HbA1c
HbA1c (mmol/mol) measured by clinical laboratory analysis of venous blood.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in HOMA index
HOMA index calculated from fasting plasma glucose and fasting insulin concentrations.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in fasting venous insulin
Fasting venous insulin concentration (pmol/L) measured by clinical laboratory analysis.
Measured: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in glycaemic control assessed by continuous glucose monitoring
Glycaemic control assessed by blinded continuous glucose monitoring using the FreeStyle Libre 3 system, with glucose values recorded at 1-minute intervals (mmol/L).
Measured: From Day 1 through Day 14
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Jul 2026
- Study start31 Aug 2026
- Primary completion28 Feb 2027 (estimated)
- Study completionMar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for FastingStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Care provider
- Enrolment
- 75 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Buchinger Wilhelmi Development & Holding GmbH
- Sponsor type
- University, hospital or other
- Collaborators
- King's College London, Faculty of Life Sciences & Medicine, Department of Nutritional Sciences, London, United Kingdom, Leiden University Medical Center, Department Leiden University Center for Infectious Diseases, 2333ZA, Leiden, Netherlands, TNO, Department Microbiology & Systems Biology, 2333 BE Leiden, Netherlands, Università degli Studi di Milano, Department of Pharmacological and Biomolecular Sciences Rodolfo Paoletti, Milan, Italy, Department of Cardio-Thoracic-Vascular Diseases, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Responsible party
- Sponsor
- Investigators
- Andrea Siegler, Dr. med., Principal investigator, Buchinger Wilhelmi Development & Holding
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07691736
- Sponsor's protocol ID
- F-2026-010
- Acronym
- CoFFIe
- Status last verified
- Sep 2026
- First submitted
- 24 Jun 2026
- Last updated
- 30 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 30 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits
- ClinicalTrials.gov ID
- NCT07691736
- Acronym / sponsor ID
- CoFFIe / F-2026-010
- Conditions
- Fasting, Dietary Fibre, Gut Microbiome, Metabolism Changes, Overweight , Obesity
- Keywords
- long-term fasting, fasting, continuous glucose monitoring, fibre supplementation, gut microbiome, metabolic health, resistant starch IV, metabolomics
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 75 participants (estimated)
- Lead sponsor
- Buchinger Wilhelmi Development & Holding GmbHUniversity, hospital or other
- Collaborators
- King's College London, Faculty of Life Sciences & Medicine, Department of Nutritional Sciences, London, United Kingdom, Leiden University Medical Center, Department Leiden University Center for Infectious Diseases, 2333ZA, Leiden, Netherlands, TNO, Department Microbiology & Systems Biology, 2333 BE Leiden, Netherlands, Università degli Studi di Milano, Department of Pharmacological and Biomolecular Sciences Rodolfo Paoletti, Milan, Italy, Department of Cardio-Thoracic-Vascular Diseases, Foundation IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Study start
- 31 Aug 2026 (actual)
- Primary completion
- 28 Feb 2027 (estimated)
- Study completion
- Mar 2027 (estimated)
- First posted
- 9 Jul 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study builds on the knowledge that fasting provides metabolic health benefits and that prebiotic interventions can enhance the gut microbiome's metabolic output to likewise improve host health. Whether long-term fasting and dietary fibre interventions could be combined to achieve synergistic improvements in host metabolic health is however unknown. The goal is to provide a proof of concept in a human trial that supplementing 10±4 days fasting with dietary fibre synergistically improves metabolic outcomes via gut microbiome-mediated effects. To assess this, we aim to analyse gut microbiome changes, functional outputs, and key metabolic markers such as butyrate production, glycaemic control and ketosis.
The randomised controlled trial includes 75 participants and has two arms: one involving fasting with fibre supplementation (n = 50) and one involving fasting without fibre supplementation (n = 25). All participants will undergo a fasting period of 10±4 days according to the Buchinger Wilhelmi protocol, followed by a stepwise reintroduction of food of up to 4 days. As dietary fibre we will use maize-derived resistant starch type IV, selected based on its ability to stimulate beneficial gut microbes like Oscillibacter and corn starch as placebo. Two main visits will be conducted: before and at the end of the fasting period. During these visits, blood and stool samples will be collected, and questionnaires will be completed. Additionally, daily measurements of anthropometric parameters and well-being will be recorded. Stool samples will also be collected one month afterwards as a follow-up. Participants' metabolic health will be evaluated through various clinical parameters (e.g., body measurements, blood pressure, glycaemic control, ketones, well-being). Additionally, multi-omics data, including metagenomics and metabolomics, will provide insight into the composition of the microbiome, as well as its outputs and functions. Furthermore, the effects of fasting on extracellular vesicles in blood will be explored.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, care provider)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Fibre Arm | Active comparator | Dietary Supplement: Fibre ArmParticipants (n=50) undergo a 10±4-day fasting period according to the Buchinger Wilhelmi fasting programme and receive maize-derived resistant starch type IV at a total dose of 20 g per day. The powder is blended into a carbohydrate-free electrolyte powder, divided into two equal daily doses, diluted in approximately 0.2 litres of water, and taken orally in the morning and at dinnertime throughout the fasting period. The fasting period is followed by a structured food reintroduction period according to the standard procedure of the Buchinger Wilhelmi Clinic. All other aspects of the intervention, including the fasting and nutritional protocol, clinical supervision, and study assessments, are identical to the control arm. |
| Control Arm | Placebo comparator | Dietary Supplement: Control ArmParticipants (n=25) undergo a 10±4-day fasting period according to the Buchinger Wilhelmi fasting programme and receive corn starch placebo at a total dose of 1.2 g per day. The powder is blended into a carbohydrate-free electrolyte powder, divided into two equal daily doses, diluted in approximately 0.2 litres of water, and taken orally in the morning and at dinnertime throughout the fasting period. The fasting period is followed by a structured food reintroduction period according to the standard procedure of the Buchinger Wilhelmi Clinic. All other aspects of the intervention, including the fasting and nutritional protocol, clinical supervision, and study assessments, are identical to the intervention arm. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Men and women
- Age: 18-65 years old
- Fasting for 10±4 days at the Buchinger Wilhelmi clinic in Überlingen
- BMI ≥ 25 kg/m²
- Signed informed consent
Key exclusion criteria (13 listed)
- intake of antibiotics up to 2 months prior the study
- regular intake of pre-, post- and probiotics up to 2 months prior the study
- diagnosed Crohn's disease, Ulcerative colitis, IBD, coeliac disease
- medicated high blood pressure
- diagnosed diabetes mellitus type I
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Fibre Arm10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 20 g/day of maize-derived resistant starch type IV. | Dietary supplement | Fibre Arm |
| Control Arm10±4 days of fasting according to the Buchinger Wilhelmi fasting protocol, followed by a structured food reintroduction period, combined with 1.2 g/day of corn starch placebo. | Dietary supplement | Control Arm |
Primary outcome
Abundance of butyrate-producing gut bacteria
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in the relative abundance of butyrate-producing gut bacteria assessed by metagenomic profiling of faecal samples.
Change in fasting venous plasma glucose
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Fasting venous plasma glucose concentration measured by clinical laboratory analysis (mmol/L).
7 secondary outcomes
Change in body weight
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in body mass index
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in waist circumference
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in HbA1c
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in HOMA index
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in fasting venous insulin
Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)
Change in glycaemic control assessed by continuous glucose monitoring
Time frame: From Day 1 through Day 14
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Sep 2026.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Andrea Siegler, Dr. med. principal investigator
Buchinger Wilhelmi Development & Holding
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Fibre Arm in people with Fasting and Dietary Fibre, run by Buchinger Wilhelmi Development & Holding GmbH at 1 site in Germany.
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 5 inclusion and 13 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: looking for participants now, as of the sponsor's last update on 30 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 1 site in Germany. 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. Some participants in this study may receive a placebo. 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?
Contact Elena Katharina Stroppel (00497551807675, katharina.stroppel@buchinger-wilhelmi.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Abundance of butyrate-producing gut bacteria (time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 30 Sep 2026.