Effect of Exercise-Induced Weight Loss on Energy Metabolism

Study Overview
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Brief Summary
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The E-MECHANIC Ancillary Study will measure changes in 24-hour energy expenditure and spontaneous physical activity in a subset of 60 obese individuals enrolled in the main study. We aim to determine if changes in energy metabolism might explain why people don't lose the expected amount of weight in an exercise program.

Detailed Description
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This is an ancillary study to E-Mechanic, which is an National Institutes of Health study in 198 individuals with the objective to understand why certain people fail to lose weight in exercise programs. In E-Mechanic changes in body weight, body composition, energy intake and energy expenditure are measured before and after 3 different exercise programs of 24 weeks in duration. The 3 exercise programs being compared are self-directed exercise, low dose exercise and high dose exercise. The goal of this ancillary study is to undertake comprehensive assessments of energy metabolism in a metabolic chamber in a group of 60 obese individuals enrolled in the main study. We will compare differences in the changes in 24h energy expenditure and spontaneous physical activity between the 3 exercise programs. We will also test if changes in energy metabolism might explain why people don't lose the expected amount of weight after 24 weeks of exercise.

Official Title
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E-MECHANIC Ancillary Study: Effect of Exercise-Induced Weight Loss on Energy Metabolism

Conditions
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Metabolism, Weight Loss

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Individuals enrolled in the E-MECHANIC main study (NCT#01264406) with a body mass index (BMI) greater than or equal to 30 kg/m2. Exclusion Criteria: Not enrolled in the E-MECHANIC main study (NCT#01264406). Have a body mass index (BMI) less than 30 kg/m2.

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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Self Directed Exercise<br>Participants randomized to the self-directed group will receive information on physical activity recommendations and guidelines on nutrition aimed at promoting weight loss. Participants will not be given a specific exercise recommendation in terms of weekly energy expenditure. | |
| Low Intensity Exercise<br>Individuals assigned to the low dose exercise group will be required to expend 8 calories per kg of body weight per week in structured aerobic exercise on a treadmill or stationary bicycle. The exercise intensity will be maintained at 65% of VO2peak. The caloric goal of each session will be calculated by dividing the weekly caloric expenditure goal by participant selected exercise frequency (i.e., 3, 4 or 5 times per week). The training program consists of a 3-min warm-up at a progressively increasing intensity until the prescribed training intensity is reached. All exercise sessions are conducted at the PBRC Fitness Center and will be supervised by staff trained on the aspects of the study protocol. | |
| High Intensity Exercise<br>Individuals assigned to the low dose exercise group will be required to expend 20 calories per kg of body weight per week in structured aerobic exercise on a treadmill or stationary bicycle. The exercise intensity will be maintained at 65% of VO2peak. The caloric goal of each session will be calculated by dividing the weekly caloric expenditure goal by participant selected exercise frequency (i.e., 3, 4 or 5 times per week). The training program consists of a 3-min warm-up at a progressively increasing intensity until the prescribed training intensity is reached. All exercise sessions are conducted at the PBRC Fitness Center and will be supervised by staff trained on the aspects of the study protocol. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in 24h energy expenditure | 24h energy expenditure will be measured in a room calorimeter before and after a 24 week exercise program | 24 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Metabolic adaptation in 24h energy expenditure | The difference between the actual change in 24 energy expenditure and the energy expenditure estimated on the basis of body size will be compared between: 1) exercise groups and 2) between individuals who lost the expected amount of weight and individuals who did not lose the expected amount of weight during the exercise program | 24 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Energy, Metabolism, Weight Loss, Exercise