Combining Fasting and Fibre Interventions to Optimise Their Gut Microbiome-mediated Health Benefits
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Fibre Arm, Control Arm.
- Who it may be relevant to
- Registry conditions: Fasting, Dietary Fibre, Gut Microbiome, Metabolism Changes. Basic parameters: 18 years — 65 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Germany
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
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.
Interventions
- Dietary supplement Fibre Arm
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. - Dietary supplement Control Arm
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.
Primary outcome measures
- Abundance of butyrate-producing gut bacteria [Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)]
- Change in fasting venous plasma glucose [Time frame: Baseline (T0) and end of the 10±4-day fasting period (T1)]
Secondary outcome measures (7)
- 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]
Eligibility criteria
Inclusion criteria
- 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
Exclusion criteria
- 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
- 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
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Parallel assignment
- Masking
- Double blind
- Primary purpose
- Prevention
Study locations
Germany · 1 center
- Buchinger Wilhelmi Development & Holding — Überlingen
Identifiers
NCT: NCT07691736 · F-2026-010