Meal Schedule Effects on Circadian Energy Balance in Adults

Study Overview
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Brief Summary
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This study will test will how eating on a particular daily schedule may effect energy, weight gain or loss, and body temperature.

Detailed Description
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Although there have been a large number of studies in humans on the effects of food intake at night, very few studies directly address the hypothesis that inappropriately phased eating or snacking (i.e., at night) in humans disrupts metabolism and respiratory quotient (RQ) patterns and there are no studies that we are aware of that directly measure circadian clock phase relative to timing of food intake while evaluating metabolism. This may be critical, because it is well established that the timing of food intake can also modulate circadian clock phase. Hypothesis: Food consumption in the subjective night (e.g., 20:00 - 02:00) will result in a different circadian metabolic profile measured by RQ) than food consumed in the subjective day. Aim 1: To determine if there are daily rhythms of switching between lipid and carbohydrate metabolism in humans that are altered by the timing of food intake. Aim 2: To determine if timing of food intake results in internal desynchronization between the metabolic rhythms (RQ) and the rhythm in core body temperature (a marker of central circadian phase). Aim 3: To determine if body composition has measurable impact on the circadian regulation of metabolism. In this study we will test human subjects in a specially designed whole-room indirect calorimeter where energy expenditure and RQ will be monitored by indirect calorimetry continuously over 56 hours. Circadian phase and amplitude will be assessed by continuously recording the core body temperature rhythm using the Vital Sense Integrated Physiological Monitoring System in which subjects swallow a telemetry capsule that transmits core body temperature to a data acquisition module. In consultation with a nutritionist at Vanderbilt, we will use a cross-over design in which daily diets have the same caloric and nutritional value but in which the subjects consume the calories that would normally be breakfast as snacks consumed in the late-evening.

Official Title
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Meal Schedule Effects on Circadian Energy Balance in Adults

Conditions
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Metabolism, Circadian Rhythms

Intervention / Treatment
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* Behavioral: Normal diet
* Behavioral: Modified diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Be able to understand the study, provide written informed consent (in English), and be able to fill out the questionnaire Be male or female older than 18 years of age; Have a normal BMI (20-25) or be obese (BMI more than 30); Have a normal basal glucose level (70-100 mg/dL) If female of childbearing potential, have a negative pregnancy test on study day; Exclusion Criteria: Be pregnant or lactating; Have known sleep, metabolic (e.g., diabetes), or gastro-intestinal disorders except obesity; Had alcohol less than 24 hours before admission; Require assistance with activities of daily living; Have difficulty swallowing Be unable to complete a food and sleep diary Be smokers

Ages Eligible for Study
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Minimum Age: 50 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: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Normal diet then modified diet<br>Participates in the normal diet will receive 3 meals each day, breakfast at 8:00 AM,lunch at 12:30 PM and dinner at 5:45 PM. Participates in the modified diet skipped breakfast, had lunch at 12:30 PM, dinner at 5:45 PM, and a breakfast equivalent snack at 10:00 PM. | Behavioral: Normal diet<br>* Participants will receive either a 2000 calorie or a 2500 calorie diet at normal meal times<br>Behavioral: Modified diet<br>* Participants will receive either a 2000 calorie or a 2500 calorie diet with a single meal shift, breakfast is moved to an hour before bedtime.<br>|
| Experimental: Modified diet then normal diet.<br>Participates in the modified diet skipped breakfast, had lunch at 12:30 PM, dinner at 5:45 PM, and a breakfast equivalent snack at 10:00 PM.Participates in the normal diet will receive 3 meals each day, breakfast at 8:00 AM,lunch at 12:30 PM and dinner at 5:45 PM. | Behavioral: Normal diet<br>* Participants will receive either a 2000 calorie or a 2500 calorie diet at normal meal times<br>Behavioral: Modified diet<br>* Participants will receive either a 2000 calorie or a 2500 calorie diet with a single meal shift, breakfast is moved to an hour before bedtime.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Oxygen intake | Subjects were housed in a whole room calorimeter and oxygen consumption was monitored minute by minute | 56 hours | 
| Carbon dioxide exhaled | Subjects were housed in a whole room calorimeter and carbon dioxide was monitored minute by minute | 56 hours | 
| Core body temperature | The subjects' circadian phase and amplitude will be assessed by continuously recording the core body temperature rhythm with an ingestible Vital Sense monitor. | 56 hours | 
| Locomotor activity | The subject's activity will be assessed throughout the experiment using a Actigraph (GT3X) triaxial monitor attached to the subject's wrist, waist, and ankle. | 56 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Determination of Body Mass Index (BMI) | A dual-energy X-ray absorptiometry (DXA) scan will be performed to assess subject's percentage body fat after check-in and before the first night in the metabolic chamber. Fat content will be used to accurately determine the subject's Body Mass Index. | Baseline just prior to entry in the metabolic chamber |