Diet, Exercise, Metabolism, and Obesity in Older Women:DEMO

Design Overview:

This study's protocol will last approximately 18 months. Phase 1 involves recruitment and screening followed by baseline research testing (Phase 2). Next, subjects will be randomly assigned to one of three 5-month treatments (Phase 3): diet and high-intensity exercise, diet and low-intensity exercise, or diet only. In the Maintenance Phase, subjects will return for visits at 6 & 12 months following the completion of their 5 month intervention.

Interventions:

All treatment groups will experience the same total weekly caloric deficit (-2800 kcal/wk), but will derive this deficit by different reductions in dietary intake and exercise energy expenditure. The weekly caloric deficit will be accomplished as follows: 1) the diet alone group will reduce dietary intake by ~2800 kcal/week (~400 kcal/day); 2) both exercise groups will expend ~400 kcal/wk in exercise energy expenditure and will reduce dietary intake by ~2400 kcal/wk (~340 kcal/day) to achieve the 2800 kcal/wk deficit.

The exercise will take place in an exercise facility at the Geriatric Research Center on the campus of the Wake Forest University/Baptist Medical Center. Two study personnel, including at least one trained technician, will supervise all exercise sessions. Emergency equipment will be kept on site during exercise sessions. Blood pressure and heart rate will be measured and recorded before each exercise session and participants will warm-up by walking for 3-5 min at a slow pace. Women will use the treadmill to exercise at an intensity of 45-50% (low-intensity AEX) or 70-75% (high-intensity AEX) of VO2max. Both groups will exercise 3 d/wk and duration of exercise will progress from 10-15 min the 1st week to 55 min by the end of the 6th week and thereafter for the low-intensity AEX group. The duration of exercise for the high-intensity AEX group will progress from 10-15 min the 1st week to 30 min by the end of the 6th week and thereafter. Injuries are minimized by a feasible progression of exercise duration as well as careful monitoring of proper footwear and stretching exercises.