Time Restricted Feeding in Male Runners

Study Overview
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Brief Summary
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This is a cross-over intervention study designed to evaluate how four weeks of time restricted feeding (16 hours fasting and 8 hours feeding), compared to four weeks of a more traditional eating pattern (12 hours fasting and 12 hours feeding), affects resting energy expenditure, subjective and biochemical markers of satiety and hunger, body composition, cardiovascular health, substrate utilization and fitness in male competitive runners.

Detailed Description
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Weight loss and improvements in body composition (increasing muscle mass and decreasing fat mass) are common goals for both dieters and athletes. Although a traditional method of achieving this has been accomplished through caloric restriction, an alternate method that is becoming increasingly popular is fasting. Fasting is described as the absence of food and/or calorie-containing beverage consumption for a period of time. The majority of people fast for 8-10 hours daily, which occurs during the overnight period when people are asleep Intermittent fasting, specifically time-restricted feeding (TRF), has recently gained popularity because it is a more sustainable means of practicing fasting and it has been shown to enhance the loss of fat mass with or without caloric restriction. It has also been shown to enhance overall health due to reports of reduced fasting glucose, insulin resistance, triglycerides, and reduced total and low-density lipoprotein (LDL) cholesterol levels in obese women. Despite its growing popularity among athletes, there is scarce research on how adhering to this type of diet pattern affects athletic performance and other biochemical markers related to health. The participants in this study will be randomly assigned to either a traditional (12/12) or a time restrictive (16/8) eating pattern in a crossover design. Each pattern will last for four weeks with a minimum two week washout in between, and the participants will consume the same calorie and macronutrient amounts based on recommendations made by the American College of Sports Medicine (ACSM) for both eating patterns. The 12/12 pattern will require subjects to consume 5 meals (breakfast, lunch, dinner, and two snacks) per day within a 12 hour period suggested to be around 8am, 10am, 12pm, 3pm, and 7pm. The 16/8 pattern will require subjects to consume 3 meals in an 8-hour period suggested to be around 12pm, 3pm, and 7pm. Subjects may only consume water, unsweetened coffee, or unsweetened tea (no artificial sweeteners) during their periods of fasting. Subjects will perform all exercise in the morning before 8 am in the fasted state. Subjects will visit the Western Human Nutrition Research Center (WHNRC) for test days at baseline (study day 1), after four weeks of the first dietary intervention (study day 28), and at the start (study day 43) and end of the second dietary intervention (study day 70), for a total of 4 test days over the duration of 10 weeks.

Official Title
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The Effects of Four Weeks of Intermittent Fasting on Resting Energy Expenditure, Satiety Hormones, Body Composition, and Performance in Competitive Runners

Conditions
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Intermittent Fasting, Athletic Performance, Fasting, Cardiovascular Risk Factor, Resting Energy Expenditure

Intervention / Treatment
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* Behavioral: Time Restrictive Feeding
* Behavioral: Traditional Eating Pattern


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Competitive runners who have been actively training for 3 or more years Weigh a minimum of 110 lbs Training 4-6 times per week and run a minimum of 20 miles per week Competed in a race within past 12 months at a distance of 5 - 26.1 km Willing to repeat same monthly training protocol during two 4-week interventions VO2max range of 40-70 ml/kg/min Exclusion Criteria: Smoker Take medications that have cardiovascular or metabolic effects Taking dietary supplements Following a restrictive diet including restricting calories or carbohydrates Evidence of an eating disorder Major injuries in past 3 months Chronic disease that affects bone health, metabolism or the cardiorespiratory system Present with any contra-indication to exercise testing (cardiovascular abnormalities) as evaluated by study physician

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 40 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: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental Group 1<br>Order of treatment, time restrictive feeding (16 hours fasting and 8 hours eating) followed by traditional eating pattern (12 hours fasted and 12 hours eating). | Behavioral: Time Restrictive Feeding<br>* Volunteers will adhere to a form of time restrictive feeding, 16 hours fasting and 8 hours eating per day.<br>* Other names: Intermittent Fasting;Behavioral: Traditional Eating Pattern<br>* Volunteers will adhere to a more traditional eating pattern, 12 hours fasted and 12 hours eating per day.<br>* Other names: Normal Diet;|
| Experimental: Experimental Group 2<br>Order of treatment, traditional eating pattern (12 hours fasted and 12 hours eating) followed by time restrictive feeding (16 hours fasting and 8 hours eating). | Behavioral: Time Restrictive Feeding<br>* Volunteers will adhere to a form of time restrictive feeding, 16 hours fasting and 8 hours eating per day.<br>* Other names: Intermittent Fasting;Behavioral: Traditional Eating Pattern<br>* Volunteers will adhere to a more traditional eating pattern, 12 hours fasted and 12 hours eating per day.<br>* Other names: Normal Diet;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in resting energy expenditure | Resting energy expenditure will be measured using a metabolic cart | Study day 1, 28, 43 and 70 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in body composition | Body composition, including fat mass and lean body mass, will be measured by dual-energy x-ray absorptiometry (DEXA) and expressed in kilograms (kg). | Study day 1, 28, 43 and 70 | 
| Change in substrate utilization during exercise | Carbohydrate and fat utilized for energy will be measured using a metabolic cart | Study day 1, 28, 43 and 70 | 
| Change in cardiovascular fitness | Time to run a 10 kilometer time trial on a treadmill expressed in minutes | Study day 1, 28, 43 and 70 | 
| Change in perceived feelings of hunger and fullness | Perceived hunger and fullness will be measured using a visual analog scale. Responses will be a mark on an unsegmented line from 0 or not at all to 5 or extremely. | Study day 1, 28, 43 and 70 | 
| Change in glucagon, a biomarker of hunger and satiety | Fasting plasma will be analyzed for glucagon (pmol/L) as measured by enzyme-linked immunoabsorbant assay | Study day 1, 28, 43 and 70 | 
| Change in leptin, a biomarker of hunger and satiety | Fasting plasma will be analyzed for leptin (pmol/L) as measured by enzyme-linked immunoabsorbant assay | Study day 1, 28, 43 and 70 | 
| Change in ghrelin, a biomarker of hunger and satiety | Fasting plasma will be analyzed for ghrelin (pmol/L) as measured by enzyme-linked immunoabsorbant assay | Study day 1, 28, 43 and 70 | 
| Change in insulin | Fasting plasma will be analyzed for insulin (pmol/L) as measured by enzyme-linked immunoabsorbant assay | Study day 1, 28, 43 and 70 | 
| Change in total cholesterol, a biomarker of cardiovascular health | Fasting serum will be analyzed for total cholesterol (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in HDL cholesterol, a biomarker of cardiovascular health | Fasting serum will be analyzed for HDL cholesterol (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in LDL cholesterol, a biomarker of cardiovascular health | Fasting serum will be analyzed for LDL cholesterol (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in very low-density lipoprotein (VLDL), a biomarker of cardiovascular health | Fasting serum will be analyzed for very low-density lipoprotein (VLDL) cholesterol (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in triglycerides, a biomarker of cardiovascular health | Fasting serum will be analyzed for triglycerides (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in alanine aminotransferase, a biomarker of cardiovascular health | Fasting serum will be analyzed for alanine aminotransferase (IU/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in aspartate aminotransferase, a biomarker of cardiovascular health | Fasting serum will be analyzed for aspartate aminotransferase (IU/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 | 
| Change in glucose | Fasting serum will be analyzed for glucose (mmol/L) by Piccolo analyzer | Study day 1, 28, 43 and 70 |