The focus of this randomized clinical trial study is an examination of the effects of maintaining energy balance at different energy fluxes. It will address the primary question: Are there increased health benefits related to body composition and metabolic function associated with maintaining energy balance at a high energy flux as compared to a low energy flux?

We will randomly assign 75 sedentary but healthy individuals to one of two exercise groups or a non-exercise group. We will follow the individuals for 6 months during the intervention period. Both groups will maintain weight by matching energy intake and expenditure (thus the exercise group will consume more calories).

Inclusion Criteria:

• BMI <35
• 21-45 years of age
• Fasting plasma glucose <126 mg/dl
• Current medications must have been prescribed for 3 or more months and stable
• Internet access
• Able to participate in a somewhat strenuous physical exercise program
• Able to provide informed consent for participation in a research study

Exclusion Criteria:

• Currently participating in a weight loss or exercise intervention / program
• Planning to have weight loss surgery
• Weight change >5 lb in last 12 months
• Currently taking any of the following: hormone replacement therapy, beta blockers, allergy shots or systematic corticosteroids (except inhalers)
• Significant cardiovascular disease or disorders including but not limited to: serious arrhythmias, cardiomyopathy, congestive heart failure, stroke or transient ischemic cerebral attacks, peripheral vascular disease with intermittent claudication, acute, chronic or recurrent thrombophlebitis, Stage II or Stage III hypertension, myocardial infarction or abnormal exercise stress test.
• Medical history with presence of significant conditions or disease that may interfere with study, recent surgery
• Pregnant or actively trying to become pregnant
• Gave birth in the last 12 months or <6 months post-lactation
• > 90th percentile on the Brief Symptom Inventory [BSI]
• Planning to move from the area in the next 8 months
• Other medical, psychiatric or behavioral factors that in the judgment of the principal investigator may interfere with study participation or the ability ot follow the intervention protocol. Upon identification of individuals with suicidal ideation or other dangerous conditions, the individual will be contacted and told to immediately go to a medical emergency room.