Bed Rest, Alternate Daily Fasting and Incretin Effect

Study Overview
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Brief Summary
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Bed rest produces insulin resistance in healthy volunteers. In this study the investigators aim to investigate the effect of 8 days bed rest on the incretin effect and how alternate daily fasting affects cognitive function and the insulin resistance produced by bed rest. The subjects will be randomized to either 3 meals a day (isocaloric diet), alternate daily fasting or one meal/day every second day (25% of daily calorie need) and four meals/day every second (175% of daily calorie need). The investigators hypothesize: Bed rest reduces the incretin effect Alternate daily fasting improves the cognitive function (memory and concentration) compared to isocaloric diet Alternate daily fasting reduces insulin resistance produced by bed rest compared to isocaloric diet

Detailed Description
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All subjects will undergo 8 days of bedrest. Outcome measures will be performed before, under and immediately after the bed rest period. The individual study period will be 10 days in total.

Official Title
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A Randomized Controlled Study on the Incretin Effect, Cognitive Function and Controlled Fasting During Bed Rest in Healthy Male Volunteers

Conditions
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Metabolic Syndrome, Type 2 Diabetes, Critical Illness

Intervention / Treatment
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* Other: Bed rest
* Other: OGTT
* Other: IVGTT
* Other: Cognitive testing
* Other: Muscle and fat biopsies
* Other: Dual-energy X-ray Absorptiometry (DXA) scan
* Other: MRI


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: BMI<25kg/m2 VO2 max normal for age Exclusion Criteria: Tobacco smoking Alcohol ingestion > 14 units per week Diabetes in nearby relatives Resection of the small intestine History of gastric bypass surgery Risk of deep venous thrombosis Female

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

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
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Isocaloric diet<br>3 daily meals | Other: Bed rest<br>* 8 days of full bed rest<br>Other: OGTT<br>* Oral glucose tolerance test with 75 g of glucose before and after bed rest<br>Other: IVGTT<br>* Intravenous glucose tolerance test mimicking the glucose profile from the corresponding OGTT<br>Other: Cognitive testing<br>* Daily testing of memory and concentration using standardized tests<br>Other: Muscle and fat biopsies<br>* Biopsies will be obtained before and after bed rest<br>Other: Dual-energy X-ray Absorptiometry (DXA) scan<br>* DXA scan to evaluate fat and muscle distribution before and after bed rest<br>Other: MRI<br>* Functional MRI to evaluate cognitive function and abdominal MRI to evaluate visceral fat before and after bed rest<br>|
| Active Comparator: Alternate daily fasting<br>One meal (25% of caloric need) every second day and four meals (175% of caloric need) every second day | Other: Bed rest<br>* 8 days of full bed rest<br>Other: OGTT<br>* Oral glucose tolerance test with 75 g of glucose before and after bed rest<br>Other: IVGTT<br>* Intravenous glucose tolerance test mimicking the glucose profile from the corresponding OGTT<br>Other: Cognitive testing<br>* Daily testing of memory and concentration using standardized tests<br>Other: Muscle and fat biopsies<br>* Biopsies will be obtained before and after bed rest<br>Other: Dual-energy X-ray Absorptiometry (DXA) scan<br>* DXA scan to evaluate fat and muscle distribution before and after bed rest<br>Other: MRI<br>* Functional MRI to evaluate cognitive function and abdominal MRI to evaluate visceral fat before and after bed rest<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incretin effect | Measured by Insulin levels during Oral glucose tolerance test (OGTT) and Intravenous glucose tolerance test (IVGTT) | 24 weeks | 
| Cognitive function | Evaluated by cognitive testing and functional Magnetic Resonance imaging (MRI) | 18 months | 
| Insulin resistance | Evaluated by insulin resistance indexes, HOMA-IR and Matsuda index | 12 weeks |