2011 Annual Report 1a.Objectives (from AD-416) Collaborate in planning, implementation and reporting of research on the effects of diet and physical activity in maintaining healthy body weight. 1b.Approach (from AD-416) Human volunteers will be studied under a variety of diety conditions and physical activity regimens, and biochemical and functional parameters will be measured. 3.Progress Report Studies were conducted to determine the effect of dietary protein level of the status of muscle protein and bone mineral during a 30-day period of negative energy balance. This was done in young men and women volunteers who lived in our metabolic unit and were subjected to a 30% energy deficit by dietary means with a 10% increase in energy output by prescribed physical activity. Bone mineral was evaluated by the retention of an infuse dose of stable calcium; protein accretion was determined by the uptake of an infused dose of stable isotopically labled amino acids into samples of thigh muscle collected by biopsy. The study was inititated in FY2011; for iterations of the study were completed in FY2011 for a total of 38 subjects. ADODR monitoring is performed via phone calls and email.