Time Restricted Feeding (4-hour Versus 6-hour) for Weight Loss in Obese Adults

Study Overview
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Brief Summary
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The aims of this proposal are to compare the effects of 4-h versus 6-h time restricted feeding (TRF) on body weight and metabolic disease risk factors in adults with obesity. To test the study objectives, a 10-week randomized, controlled, parallel-arm trial, divided into 2 consecutive periods: (1) 2-week baseline period; and (2) 8-week TRF weight loss period, will be implemented. Obese subjects will be randomized to 1 of 3 groups: (1) 4-h TRF, (2) 6-h TRF, or a no-intervention control group. This study will be the first randomized controlled trial to compare 4-h versus 6-h TRF.

Detailed Description
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Modest weight loss of 5-10% is sufficient to reduce metabolic disease risk in obese individuals. The first line of therapy prescribed for weight loss is daily calorie restriction (CR; 25% restriction every day). However, adherence to CR greatly diminishes after 4-6 weeks, due to subject frustration with constantly having to count calories and never being able to eat freely. In light of these issues with CR, another approach that limits timing of food intake, instead of number of calories consumed, has been developed. This strategy is termed time restricted feeding (TRF), and involves confining the period of food intake to 8 h/d (10 am to 6 pm) without calorie counting. Preliminary findings of 8-h TRF demonstrate modest weight loss and blood pressure reductions after 12 weeks. What remains unknown however, is whether shorter feeding windows during TRF (such as 4-h or 6-h feeding windows) can produce even greater weight loss in obese adults. Also of interest, is the impact of these shorter feeding windows on metabolic disease risk indicators (such as plasma lipids, blood pressure, and insulin resistance, inflammation and oxidative stress). Accordingly, the aims of this proposal are: AIM 1: To compare the effects of 4-h versus 6-h time restricted feeding (TRF) on body weight in adults with obesity; AIM 2: To compare the effects of 4-h versus 6-h TRF on metabolic disease risk factors in adults with obesity. To test the study objectives, a 10-week randomized, controlled, parallel-arm trial, divided into 2 consecutive periods: (1) 2-week baseline period; and (2) 8-week TRF weight loss period, will be implemented. Obese subjects will be randomized to 1 of 3 groups: (1) 4-h TRF, (2) 6-h TRF, or a no-intervention control group. This study will be the first randomized controlled trial to compare 4-h versus 6-h TRF on body weight and metabolic disease risk markers.

Official Title
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Time Restricted Feeding (4-hour Versus 6-hour) for Weight Loss in Obese Adults

Conditions
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Obesity, Diabetes

Intervention / Treatment
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* Behavioral: Time restricted feeding


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female; body mass index (BMI) between 30.0 and 49.9 kg/m2; age between 18 and 65 years; sedentary (light exercise less than 1 h per week) or moderately active (moderate exercise 1 to 2 h per week); weight stable for >3 months prior to the beginning of the study (gain or loss <4 kg); able to give written informed consent Exclusion Criteria: Smoker; diabetic; taking weight loss medications; taking medication that requires eating food before (or with) the medication; history of eating disorders; night-shift workers; perimenopausal; pregnant women

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 4-hour Time restricted feeding<br>4-h TRF subjects will consume food ad libitum between 3pm and 7pm (4-h feeding window), and refrain from eating and drinking caloric beverages from 7pm to 3pm (20-h fasting window) each day. These subjects will not be instructed to limit/monitor energy intake during the feeding window. Subjects will be encouraged to drink plenty of water during the fasting period. | Behavioral: Time restricted feeding<br>* TRF subjects will consume food ad libitum during the feeding window (4-h or 6-h window), and refrain from eating during the fasting window (20-h or 18-h window)<br>|
| No Intervention: Control<br>Controls will be instructed to maintain their weight throughout the trial, and not to change eating or physical activity habits. Controls will visit the research center at the same frequency as the TRF groups (for outcome measurements). | |
| Experimental: 6-hour Time restricted feeding<br>6-h TRF subjects will consume food ad libitum between 1pm and 7pm (6-h feeding window), and refrain from eating and drinking caloric beverages from 7pm to 1pm (18-h fasting window) each day. These subjects will not be instructed to limit/monitor energy intake during the feeding window. Subjects will be encouraged to drink plenty of water during the fasting period. | Behavioral: Time restricted feeding<br>* TRF subjects will consume food ad libitum during the feeding window (4-h or 6-h window), and refrain from eating during the fasting window (20-h or 18-h window)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline to week 8 in body weight | Measured by an electronic scale | Measured at week 1 and 8 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline to week 8 in body composition | Measured by DXA | Measured at week 1 and 8 | 
| Change from baseline to week 8 in Insulin resistance | Measured as HOMA-IR | Measured at week 1 and 8 | 
| Change from baseline to week 8 in Fasting glucose | Measured with a hexokinase reagent kit | Measured at week 1 and 8 | 
| Change from baseline to week 8 in Fasting insulin | Measured as total immunoreactive insulin | Measured at week 1 and 8 | 
| Change from baseline to week 8 in Blood pressure | Measured by a blood pressure cuff | Measured at week 1 and 8 | 
| Change from baseline to week 8 in adverse events | Measured by questionnaire | Measured weekly from baseline to week 8 | 
| Change from baseline to week 8 in plasma lipids | Measured by outside lab (Medstart, IN) | Measured at week 1 and 8 | 
| Change from baseline to week 8 in heart rate | Measured by a blood pressure cuff | Measured at week 1 and 8 | 
| Change from baseline to week 8 in inflammatory markers (TNF-a, IL-6) | Measured by ELISA | Measured at week 1 and 8 | 
| Change from baseline to week 8 in oxidative stress (8-isoprostane) | Measured by ELISA | Measured at week 1 and 8 | 
| Change from baseline to week 8 in calorie and macronutrient intake | Measured by food record | Measured at week 1 and 8 | 
| Change from baseline to week 8 in physical activity (steps/d) | Measured by activity monitor | Measured at week 1 and 8 | 
| Change from baseline to week 8 in diet adherence | Measured by a questionnaire | Measured weekly from baseline to week 8 | 
| Change from baseline to week 8 in sleep quality | Measured by a questionnaire | Measured at week 1 and 8 | 
| Change from baseline to week 8 in insomnia severity | Measured by a questionnaire | Measured at week 1 and 8 | 
| Change from baseline to week 8 in risk of sleep apnea | Measured by a questionnaire | Measured at week 1 and 8 | 
| Change from baseline to week 8 in sex steroid levels (estrogen, androgens, sex hormone binding globulin) | Measured by a ELISA | Measured at week 1 and 8 |