Aim of the study is to compare the origin of ketone bodies: endogenous ketone bodies due to 36 hours fasting or 24 hours of ketogenic diet vs. exogenous ketone bodies as supplements additional to normal diet. Secondary aim of the study is to validate the new metabolic chambers.
Each study week starts with a 3-day run-in period with controlled diet at home and ends with a test-meal (breakfast) in the lab and following food record over the rest of the day at home. 1. week: physical activity level (PAL) 1.3, 3 intervention days in the metabolic chamber: ad libitum energy intake, washout day, isocaloric diet, 36 hours fasting 2. week: physical activity level (PAL) 1.3, 2 intervention days in the metabolic chamber: isocaloric diet, 36 hours fasting 3. week: physical activity level (PAL) 1.6, 2 intervention days in the metabolic chamber: ad libitum energy intake, 36 hours fasting 4. week: physical activity level (PAL) 1.6, 2 intervention days in the metabolic chamber: isocaloric diet, ketogenic diet (isocaloric) 5. week: physical activity level (PAL) 1.6, 2 intervention days in the metabolic chamber: isocaloric diet, isocaloric diet + ketone body supplements (isocaloric)
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
8
24 hour intervention with ketone body supplements additional to a normal diet (isocaloric diet in total) to induce ketosis (exogenous ketone bodies), in a metabolic chamber at physical activity level of 1.6, after one day of isocaloric diet in a metabolic chamber at physical activity level of 1.6.
24 hour interventions with ketogenic isocaloric diet to induce ketosis (endogenous ketone bodies), in a metabolic chamber at physical activity level of 1.6, after one day of isocaloric diet in a metabolic chamber at physical activity level of 1.6.
Institute of Human Nutrition
Kiel, Germany
appetite control - ghrelin
ghrelin concentration in plasma (24 hour AUC)
Time frame: 24 hours
appetite control - GLP-1 concentration in plasma
Glucose Like Peptide-1 concentration in plasma (24 hour AUC)
Time frame: 24 hours
appetite control - PYY concentration in plasma
Peptide YY concentration in plasma (24 hour AUC)
Time frame: 24 hours
appetite control - subjective feelings of hunger
measured with visual analogue scales (24 hour AUC). The scale consists of a 10 cm vertical line anchored with "not hungry at all" at the left side and with "extremely hungry" at the right side.
Time frame: 24 hours
appetite control - satiety quotient
satiety quotient of standard test-breakfast after 24 hours of intervention
Time frame: 30 min
macronutrient oxidation
measured with indirect calorimetry in a metabolic chamber
Time frame: 24 hours
energy expenditure
measured with indirect calorimetry in a metabolic chamber
Time frame: 24 hours
glycemia - glucose AUC
glucose AUC from continuous glucose monitoring data
Time frame: 24 hours
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36 hours of fasting, in a metabolic chamber at physical activity level of 1.6, after one day of isocaloric diet in a metabolic chamber at physical activity level of 1.6.
36 hours of fasting, in a metabolic chamber at physical activity level of 1.3, after one day of isocaloric diet in a metabolic chamber at physical activity level of 1.3. The same intervention is reproduced one week later.
repeatability of energy expenditure measurements
repeated measurement of 24h-energy expenditure in a metabolic chamber on inactive isocaloric and fasting days
Time frame: 24 hours
ß-Hydroxybutyrate concentration in serum
24 hour ß-Hydroxybutyrate concentration in serum (AUC)
Time frame: 24 hours