Fat Cell Size and Overfeeding and Etopic Study

Study Overview
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Brief Summary
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It has been shown that large fat cells are associated with more risks for insulin resistance and more cardiovascular risk factors such as high cholesterol or triglycerides.

Detailed Description
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This study will look at fat cell size and how it affects fat deposition, insulin resistance and muscle oxidative capacity. A comparison will be made with the differences between participants with larger versus smaller fat cells in insulin resistance and blood levels of lipids. The study will also determine if characteristics of fat cells and muscle can predict the development of weight gain-induced insulin resistance.

Official Title
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Fat Cell Size and Overfeeding and Etopic Study

Conditions
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Over Eating

Intervention / Treatment
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* Other: Overfeeding


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Your Body Mass Index (height to weight ratio) is 22.5 to 32.5 (inclusive). You are 18-40 years of age. You are willing to enroll in an 8 week overfeeding study causing a 5-8 % weight gain. You are willing to eat all your meals from Pennington and only meals from Pennington for approximately 10 weeks total, even when you are full. Prior to overfeeding 2 Meals per day will be served at Pennington with lunch packed for at least 7 days. After that time participants will receive and eat all (overfeeding) meals at PBRC for 8 weeks. Post-overfeeding will consists of weight-maintenance diet for 1 week. All meals will be monitored at Pennington. You are willing to maintain the same level of exercise after enrollment in the study throughout the length of the study. You are willing to complete nutritional and activity questionnaires. Exclusion Criteria: You weight > 300 lbs You have a history of cardiovascular disease or diabetes. You have a fasting blood glucose > 110 mg/dL. You have an average screening blood pressure > 140/90. You have liver disease. You have thyroid disease. Have Acid Reflux Had cancer in the last 5 years (Some skin cancers OK) Have HIV Have had an Eating Disorders You are pregnant or breastfeeding. You have gained or lost more than 3kg in the last 3 months You require chronic use of medications including diuretics, steroids and adrenergic-stimulating agents. You or a member of your family has a history of blood clots (deep vein thrombosis or pulmonary embolism) You have poor circulation, history of bypass operation in your legs, blood coagulation disorders, diagnosed peripheral arterial or vascular disease, cramping pain in your leg muscle during exercise or nerve damage to your legs You have varicose veins (per discretion of MD or NP) You have had previous GI surgery, obstructive disease of the GI tract, hyper motility disorder or a history of problems of impairment of the gag reflex. You have emotional problems such as clinical depression or other diagnosed psychological conditions. You are claustrophobic. You have metal objects in your body such as implanted rods or surgical clips or magnetic objects that are incompatible with the MRI/MRS. You smoke or use tobacco products

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 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: Other
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Overfeeding<br>We overfed 40 young, healthy adults by 40% of their baseline energy requirements for 8 weeks. The diet consisted of 41% carbohydrate, 44% fat, and 15% protein. | Other: Overfeeding<br>* We overfed 40 young, healthy adults by 40% of their baseline energy requirements for 8 weeks. The diet consisted of 41% carbohydrate, 44% fat, and 15% protein.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Determine the effect of 8-weeks 40% high fat overfeeding in 40 healthy, young adults on adipose and skeletal muscle characteristics, ectopic fat accumulation, insulin sensitivity, and metabolic flexibility. | This study will investigate how fat cell size (independent of total fat mass) affects metabolic outcomes of overfeeding, including changes in fat deposition, insulin sensitivity and muscle oxidative capacity. It has been shown that large fat cells relative to fat mass are associated with higher risks for insulin resistance and type 2 diabetes. | 10 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fat Deposition | Viewing of adipose tissue or body fat and skeletal muscle characteristics over a period. | 10 Months | 
| Insulin Sensitivity | Measure and monitor the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse heealth effects, depending on dietary conditions or sensitivity of cells to insulin. | 10 months | 
| Muscle Oxidative Capacity | A measure of a muscle's maximal capacity to use oxygen in microliters of oxygen consumed per gram of muscle per hour. | 10 Months | 
| Circadian Blood Pressure variability | Blood pressure and heart rate measurement: An automatic BP monitoring device (Mortara® Ambulo 2400) for ambulatory use was attached to a BP cuff to obtain blood pressure (BP) and heart rate (HR) readings at 30-min intervals during the day (6:30 AM to 9:30 PM) and 60-min intervals at night (10 PM to 6 AM) while the participants went about their activities. Data were downloaded into the database at the end of the 7-day recording span for a chronobiological analysis. This was done at baseline, post-overfeeding and at 3 months. | 10 Months | 
| Resting Endothelial function testing | Endothelial function testing: Assessment of resting endothelial function was done with the participant in a fasting state, after having avoided stimulants (caffeine, tobacco, alcohol, exercise) for 12 hours, at the same fixed clock hour (range 8-10 AM), using the EndoPAT 2000 device manufactured by ITAMAR Medical®. | 10 Months |