12-Week Diet and Exercise Intervention. The intervention is based on the research team's successful prior work in behavioral interventions. During the 12-week intervention, all participants will participate in a diet and exercise program. Exercise: Participants will attend a supervised exercise program, 10 subjects per group meeting 3x/wk. The program will begin with exercise for 20 minutes at a moderate intensity (determined during initial exercise testing). After week 2, exercise will be increased to 30 minutes; and after week 3, exercise will be increased to 50 minutes, resulting in 150 minutes of supervised exercise weekly. Exercise will be preceded by a 10 minute warm-up and a 10 minute cool down following exercise. The exercise classes will be held at the University of Wisconsin Natatorium (see letter of support), which includes stationary bikes, treadmills, elliptical machines, etc. Participants will be encouraged to exercise on their own for 30-50 minutes at least 2 days/week for a total of 5 days/week of exercise. Participants will be provided with heart rate monitors and instruction on how to use them to maintain a target heart rate during exercise. Anaerobic threshold measured during baseline testing will be used initially to determine target heart rate, but participants will be monitored every other week during the exercise sessions using heart rate variability techniques published by the Co-PI, R. Gretebeck to adjust for improvements in exercise capacity54. Diet: Participants will be instructed by a dietitian (Co-PI, Dr. R. Gretebeck) to follow a diet designed to reduce post prandial and overall glucose levels. The American Diabetes Association approves the use of a CRD in overweight or obese individuals, but cautions that this approach should be limited to one year. There is no consensus on the definition of a CRD, but most studies have used diets providing between 30-100g of carbohydrates per day accompanied with a moderate amount of protein (15-30% of calories), with fats providing the rest of daily energy requirements. For this study, participants will be instructed to avoid or restrict grains, sugars, legumes, starchy vegetables, and fruits. Carbohydrate from dairy, condiments, nuts and seeds etc. will not be limited, resulting in a diet that is not considered severely restricted and thus easier to follow, but still less than 100g of carbohydrates per day. In concrete terms, most meals will include some source of animal protein including dairy products with non-starchy vegetables and fat from sources such as olive oil, avocado, nuts, butter and cheese. Behavior Change: The dietitian (who is also an exercise physiologist) and Co-I, K. Gretebeck, behavior change expert, will conduct a weekly 30-minute behavior change class with the focus on self-regulation (goal setting, self-monitoring, relapse prevention, overcoming barriers, etc.) to promote diet and exercise adherence. Specific emphasis will be placed on glucose self-monitoring for immediate feedback of glycemic control. Building on the behavior change classes, the study investigators will use glucose self-monitoring as an immediate feedback loop to motivate participants to maintain normalized or improved glucose homeostasis through diet and exercise. Following the 12-week diet and exercise intervention, participants will continue to self-monitor their blood glucose, and continue the diet and exercise program on their own. After the 12 week intervention, investigators will meet with participants monthly to collect blood and urine for metabolomics, and download the glucose history from the glucose monitors. The following objective measures will be used to assess adherence to the lifestyle intervention: history of glycemic control from glucose monitors, HOMA-IR, exercise capacity (V02 max), 6 minute walk, and metabolomic changes.