Physiological Response to 5 Days Fasting

Study Overview
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Brief Summary
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To investigate energy metabolism, anthropometry, blood pressure, gut microbiome, serum metabolome, glucose variability and neural mechanisms of food choice and mood before and after 5 days of fasting as well as their persistence in healthy men and women.

Official Title
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Physiological Response to Prolonged Fasting in Healthy Volunteers

Conditions
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Healthy

Intervention / Treatment
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* Other: Buchinger fasting


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women 20-50 years Body mass index 20-30 kg/m2 Exclusion Criteria: Clinically relevant heart, lung, liver, and kidney diseases Any prescribed medication (except for oral contraceptives) Current or chronic infection Intake of antibiotics within 6 months before study entry Fasting week within 6 months before study entry Habitual use of dietary supplements Food intolerances Pregnancy, lactation Vegan diet Smokers In addition for fMRI: sensorineural hearing loss, tinnitus, metal implants, electric devices

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Waiting list control group
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Fasting<br>Starts immediately with 5 days of Buchinger fasting | Other: Buchinger fasting<br>* Caloric intake of < 250 kcal/d for 5 days<br>|
| Placebo Comparator: Waiting list control<br>Starts with 5 days of Buchinger fasting after a waiting period of 12 weeks | Other: Buchinger fasting<br>* Caloric intake of < 250 kcal/d for 5 days<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Resting Energy Expenditure | Measured by indirect calorimetry (kcal/d) | 6-th day of fasting compared to baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Resting Energy Expenditure - Recovery | Measured by indirect calorimetry (kcal/d) | 12 weeks after fasting compared to baseline | 
| Resting Respiratory Exchange Ratio | Measured by indirect calorimetry | 6-th day of fasting and 28 days after fasting compared to baseline | 
| Office systolic blood pressure | Mean of five consecutive blood pressure measurements (mmHg) | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Office diastolic blood pressure | Mean of five consecutive blood pressure measurements (mmHg) | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Fecal microbiome composition | Measured by 16S Sequencing | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Fecal and serum metabolome | Measured by mass spectrometry | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Change in immune cell phenotypes | Peripheral blood effector T cell frequencies (Percent) | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Glucose variability | Measured by continuous glucose monitoring over 14 days | From 3 days before until 6 days after fasting | 
| Neural correlates of emotion processing | Measured by functional Magnetic Resonance Imaging | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Neural correlates of food-specific delay discounting | Measured by functional Magnetic Resonance Imaging | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Perceived Stress Questionaire (PSQ) | Range 0-100, with 0 indicating no perceived stress | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| Perceived Self Efficiency | Range 10-40, with 40 indicating highest self efficiency | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| PANAS Positive Affect Subscale (GESIS Panel) | Range 10-50, with 50 indicating highest positive affect | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| PANAS Negative Affect Subscale (GESIS Panel) | Range 10-50, with 50 indicating highest negative affect | 6-th day of fasting and 12 weeks after fasting compared to baseline | 
| International Physical Activity Questionaire (IPAQ, long version) | Time for moderate and vigorous activity (hours, minutes) | 6-th day of fasting and 12 weeks after fasting compared to baseline |