PRO diet recommendations will include high quality proteins with an emphasis on lean meats, with protein being targeted for every meal and snack. PRO will provide dietary protein (1.6 g.kg-1.d-1; ~30% of energy intake) with a ratio of carbohydrate/protein of <1.5 and dietary lipids at ~ 30% energy intake. Energy deficit will be determined by reducing estimated daily energy needs by ~500 kcal/d. The prescribed diet will include a minimum of one serving of beef per day, which is approximately 3 to 3.5 ounces or ~100 grams. The exercise program will require attendance of 3 nonconsecutive days per week. A program that combines flexibility and balance activities, weight bearing endurance exercise (walking) and resistance training to preserve lean mass will be prescribed. Each session will last ~75 min with a 35 min warm-up/aerobic exercise of mild to moderate intensity, ~30 min of resistance training, and finally, a ~10 min of balance and flexibility exercises during the cool-down period.

PRO diet recommendations will include high quality proteins with an emphasis on lean meats, with protein being targeted for every meal and snack. PRO will provide dietary protein (1.6 g.kg-1.d-1; ~30% of energy intake) with a ratio of carbohydrate/protein of <1.5 and dietary lipids at ~ 30% energy intake. Energy deficit will be determined by reducing estimated daily energy needs by ~500 kcal/d. The prescribed diet will include a minimum of one serving of beef per day, which is approximately 3 to 3.5 ounces or ~100 grams.

Diet will provide dietary protein at 0.8 g.kg-1.d-1 (~ 18% of energy intake) with a ratio of carbohydrates/protein > 3.5 and dietary lipids at ~30% energy intake. Again, energy deficit will be determined by reducing estimated daily energy needs by ~500 kcal/d. The exercise program will require attendance of 3 nonconsecutive days per week. A program that combines flexibility and balance activities, weight bearing endurance exercise (walking) and resistance training to preserve lean mass will be prescribed. Each session will last ~75 min with a 35 min warm-up/aerobic exercise of mild to moderate intensity, ~30 min of resistance training, and finally, a ~10 min of balance and flexibility exercises during the cool-down period.

PRO+EX and CARB+EX groups will be prescribed an exercise program with required attendance of 3 nonconsecutive days per week. Exercise sessions will be supervised and conducted by trained graduate students in the Department of Kinesiology. Based on recommended practice, a program that combines flexibility and balance activities, weight bearing endurance exercise (walking) and resistance training to preserve lean mass will be prescribed. Each session will last ~75 min with a 35 min warm-up/aerobic exercise of mild to moderate intensity, ~30 min of resistance training, and finally, a ~10 min of balance and flexibility exercises during the cool-down period. Endurance training activities will vary but will all be weight-bearing.

Abdominal visceral and subcutaneous adiposity and muscle area and adipose infiltration of muscle will be measured using proton-weighted MR imaging. Subjects will be positioned feet first and supine in a 3.0 Tesla whole body imager (Signa, General Electric, Milwaukee, WI, USA). Imaging of the abdominal region and the thigh will be performed with two separate imaging sequences. The following pulse sequence parameters will be used: Fast Spin Echo-XL, TR/TE = 700/8.12 ms; Slice Thickness = 10mm; NEX = 3; Gap thickness = 5mm; ETL = 3; FA = 90; Number of slices = 18; Acquisition Matrix = 320 x 224 (Reconstructed = 512 x 512); FOV = 20cm; Voxel Size = .39 x .39 x 10 mm. Following high resolution T1 imaging, the images will be analyzed to determine the relative amount of fat in images using a modified Dixon method.

Whole body fat mass, lean mass and bone mass will also be assessed with DXA scanning.

Using an isokinetic dynamometer (Biodex System Pro 4, Biodex Medical Systems, INC., New York) with the participant positioned according to manufacturer guidelines, four maximal knee extension and knee flexion contractions will be performed and measured at 0, 60 and 180 deg/sec with the testing order (left, right) and velocity (fast, slow, zero) randomized. The isometric (0 deg/sec) effort will be held for 4-seconds. A set of 25 consecutive maximal repetitions at 180 deg/sec will be used to assess muscular endurance.

Subjects will take the following battery of psychological questionnaires at three timepoints: Profile of Mood States, Self-Motivation Inventory, Labeled Magnitude Scale, Affect Grid, SF-36, Pittsburgh Sleep Quality Index, Center for Epidemiological Studies Depression Scale, Perceived Stress Scale, WEL Self-Efficacy Questionnaire, Three Factor Eating Questionnaire, Mini-Mental Status, and the Trails B.

A battery of tests will assess multiple components of physical function, including static and dynamic balance, agility, muscular strength and power, and aerobic capacity.