Obese older adults (≥60 yrs) with moderate functional impairment will be randomized to 1 of 2 study arms. Outcomes to be measured at 0, 3 and 6 months are as follows: Primary outcomes- (1) Muscle Quality (MQ): muscle power (time to perform ten chair rises, height of the chair, leg length, body mass, and acceleration of gravity) in relation to muscle mass (CT-scan) and (2) Muscle adipose infiltration (MAI) (CT-scan). Secondary outcomes- Bone Mineral Density (BMD; DXA scan) physical function (Short Physical Performance Battery (SPPB); 6 minute walk; 8-foot up and go; and 30 second chair stands; handgrip strength; body weight; fat mass; waist circumference; activity (accelerometers); mental health (sleep, depression, quality of life); and feasibility factors (adherence, protein intake, nutrition adequacy). BMD will only be accessed at 0 and 6 months.
Study Arms:
* Weight loss plus low-intensity exercise intervention (WL-LoEX; n = 35): Subjects follow a calorie-reduction diet for a weight loss of ≥10%, protein\~0.8g/g/d. Subjects will also participate in three 30-minute low-intensity exercise sessions weekly. One serving of dairy protein/day will be provided to WL-LoEX participants.
* High protein weight loss plus low-intensity exercise intervention (PRO-WL-LoEX; n = 35): Subjects follow a calorie-reduction diet for a weight loss of ≥10%, with a high proportion of high quality protein at each meal. Intakes of \> 30g of protein will be achieved three times a day by subjects in this group, with all or predominantly all from animal sources (high quality) and 60-70% of animal protein from dairy foods that will be provided. Subjects will also participate in three 30-minute low-intensity exercise sessions weekly.
