Ketogenic Diet - a Randomized, Controlled, Cross-over Study

Study Overview
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Brief Summary
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The investigators planned study is a randomized, controlled exploratory study of a ketogenic and a NFA (National Food Administration) recommended diet. Study participants will be female nutrition students with both knowledge and interest in dietary surveys, in order to increase motivation and adherence. They will be provided with cooked food. The women should be weight stable and maintain their physical activity during the study, in order to evaluate how the diet itself affects various health parameters. The investigators intend to investigate diet specific biomarkers (small molecules involved in metabolism) in the blood, as well as blood lipids, body composition, gut microbiota, energy substrate utilization, exercise performance, resting metabolic rate, hormones, cognition and sweet cravings. In addition, the investigators intend to qualitatively study the experience of following both of these dietary regimes. The investigators intend to make a short and controlled study. The study is expected to reveal whether the ketogenic diet is a healthy or unhealthy diet in the short term. The investigators also expect that data from this study will be a helpful tool to measure diet adherence in future long-term studies.

Detailed Description
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Aim: The aim of this randomized controlled exploratory study is to study effects of a ketogenic diet (a low carb - high fat (LCHF) diet) compared to a National Food Administration (NFA) recommended diet (NNR2012). Primary outcomes are blood lipids and diet specific biomarkers. Power calculations show that 20 participants are needed to obtain significant results with 90% power at the 95% significance level for the primary outcome small-dense LDL (blood lipids). The investigators calculate that 20% of the participants will drop out before the end of the study, and therefore the investigators aim to recruit a total of 24 participants. Secondary outcomes are body composition, gut microbiota, energy substrate utilization, exercise performance, resting metabolic rate (RMR), hormones, cognition, sweet cravings, and the experience of following the two dietary regimes. Study design: Study participants will be female nutrition students with both knowledge and interest in dietary surveys, in order to increase motivation and adherence. The women should be weight stable and maintain their physical activity during the study, in order to evaluate how the diet itself affects various health parameters. Study participants will be provided with all food in the diet intervention. The amount and source of fat, protein and carbohydrates in the two diets are strictly defined; LCHF: Maximum 25 g carbohydrates/day (approximately 5 E%), 20 E% protein and 75 E% fat (35 E% saturated fat). NNR2012: 50 E% carbohydrates, 20 E% protein and 30 E% fat (10 E% saturated fat). Study participants will be randomized with respect to their physical activity level to one of two study arms, with crossover design: Study arm 1: LHCF (4 weeks) --- washout (15 weeks) --- NNR (4 weeks) Study arm 2: NNR (4 weeks) --- washout (15 weeks) --- LCHF (4 weeks) Study participants will eat each diet for four weeks. The different diets are separated by a washout period when they eat as usual. Every morning during each four-week diet period the participants will measure their urine ketones by using urine ketone strips, weigh themselves and record their body weight. Any discrepancies in food intake will be recorded in a log book in which also the daily physical activity level is specified. Energy expenditure will be measured for three days during the four week periods using SenseWear activity meter (a validated and objective method) to see if energy intake matches energy expenditure. Baseline- and outcome measurements will be performed prior to and at the end of each four-week diet period. Qualitative measurements: When the whole diet study is completed and the research subjects have experience of eating both NNR and LCHF diet interviews will be conducted with some of the research subjects. The study is expected to reveal whether LCHF is a healthy or unhealthy diet in the short term. The investigators also expect that data from this study will be a helpful tool to measure diet adherence in future long-term studies.

Official Title
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A Randomized Controlled Diet Intervention Comparing Effects of a Ketogenic Diet Versus a National Food Administration Recommended Diet Among Healthy Female Adults

Conditions
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Healthy

Intervention / Treatment
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* Other: Ketogenic diet for four weeks, then a 15 week washout, and finally a NFA recommended diet for four weeks
* Other: NFA recommended diet for four weeks, then a 15 week washout, and finally a ketogenic diet for four weeks.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Female Age 18-30 BMI 18,5-25 Exclusion Criteria: Waist circumference ≥80 cm Gravidity Diabetes Thyroid disease Prescribed medication for high cholesterol or high blood pressure Nicotine use Eating disorder Dietary restrictions

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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No

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: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Ketogenic diet first<br>Starting with ketogenic diet first and then switching to a NFA recommended diet | Other: Ketogenic diet for four weeks, then a 15 week washout, and finally a NFA recommended diet for four weeks<br> <br> |
| Experimental: NFA recommended diet first<br>Starting with NFA recommended diet first and then switching to a ketogenic diet | Other: NFA recommended diet for four weeks, then a 15 week washout, and finally a ketogenic diet for four weeks.<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Biomarkers in blood Measured with gaschromatography (GC)-time-of-flight/mass spectrometry (MS) and Bio-Plex Assays | Measured with gaschromatography (GC)-time-of-flight/mass spectrometry (MS) and Bio-Plex Assays | baseline - four weeks | 
| Blood lipids Measured with LipoPrint System | Measured with LipoPrint System | baseline - four weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body composition Measured with DXA (Dual Energy X-Ray Absorptiometry) | Measured with DXA (Dual Energy X-Ray Absorptiometry) | baseline - four weeks | 
| Gut microbiota measured with High-throughput sequencing of nucleic acids (DNA/RNA), short-chain fatty acids | High-throughput sequencing of nucleic acids (DNA/RNA), short-chain fatty acids | baseline - four weeks | 
| Energy substrate utilization during submaximal exercise Measured with indirect calorimetry during ergometer cycling, lactate in blood. | Measured with indirect calorimetry during ergometer cycling, lactate in blood. | baseline - four weeks | 
| Exercise performance | Cycling at a sub-maximal work rate with increments every 4 min for three periods, thereafter increased work rate every minute until voluntary exhaustion. | baseline - four weeks | 
| Hand grip endurance | Hand grip test. | baseline - four weeks | 
| Resting metabolic rate Measured with indirect calorimetry | Measured with indirect calorimetry (Quark RMR, COSMED) | baseline - four weeks | 
| Hormones Measured with Bio-Plex Assays and ELISA | Measured with Bio-Plex Assays and ELISA | baseline - four weeks | 
| Cognition Measured with the Stroop color-word test | Measured with the Stroop color-word test | baseline - four weeks | 
| Sweet cravings Measured with a likert scale questionnaire | Measured with a likert scale questionnaire | baseline - four weeks | 
| Mood and appetite Measured with a likert scale questionnaire | Measured with a likert scale questionnaire | baseline - every third day during the diet intervention period - four weeks | 
| Experiences of following a particular dietary regime measured with Semi-structured interviews analyzed with content analysis | Semi-structured interviews analyzed with content analysis | After finishing both study arms |