Caloric Restriction, Exercise, and Glucoregulation in Humans (CREG)

Weight loss induced by caloric restriction alone (CR) and by exercise alone (EX) result in similar effects on blood glucose and insulin. The purpose of this study is to assess the hypothesis that weight loss through caloric restriction plus exercise will result in greater improvements on glucose tolerance and insulin action than similar weight losses through CR or EX alone.

Participants are randomized into caloric restriction, exercise, and caloric restriction plus exercise weight loss groups. Measurements of blood glucose, oral glucose tolerance, and matched glucose infusion will be done at baseline and after weight loss of 6% of body weight. Other tests include maximal oxygen uptake (VO2max), strength tests, blood pressure, dual X-ray absorptiometry (DEXA) for bone density and lean body mass, lung diffusion, and cardiac output/lung capacity.

• Other: Calorie Restriction
  This group will undergo a 20% reduction in energy intake without any change in energy expenditure.
• Other: Exercise
  This group will undergo a 20% increase in energy expenditure by exercising without any change in energy intake.
• Other: Calorie Restriction and Exercise
  This group will undergo 10% reduction in energy intake and a 10% increase in energy expenditure via exercise.

• Active Comparator: Calorie restriction
  Intervention: Other: Calorie Restriction
• Active Comparator: Exercise
  Intervention: Other: Exercise
• Experimental: Calorie restriction and exercise
  Intervention: Other: Calorie Restriction and Exercise

Inclusion Criteria:

• females postmenopausal
• no diabetes, cardiovascular disease, cancer
• no orthopedic problems
• not currently exercising
• BMI between 25 and 29.9
• nonsmokers

Exclusion Criteria:

• current regular exercisers
• premenopausal women
• cardiovascular disease, lung disease, cancer, diabetes