"Skeletal Muscle Responses to Negative Energy Balance: Effects of Dietary Protein"
http://advances.nutrition.org/content/3/2/119.full#F1Highlights from review:
*Sustained periods of negative energy balance decrease body mass due to losses of both fat and skeletal muscle mass
*In general, the proportion of body mass loss at the recommended dietary allowance of protein (0.8 g·kg−1·d−1) is: ~75% adipose tissue and ~25% fat-free mass
*Consuming a high-protein diet may contribute to the regulation of muscle mass by maintaining whole-body protein turnover in response to either acute or prolonged periods of negative energy balance
*A high protein diet during most studies was 1.5 g·kg−1·d−1, nearly twice the recommended dietary allowance of 0.8 g·kg−1·d−1
*A study of nitrogen balance in healthy volunteers with an aerobic exercise-induced deficit of 1000 kcal/d demonstrated that a protein intake of 1.8 g·kg−1·d−1 abrogated a negative nitrogen balance
mechanisms of protective effect are poorly understood
*leucine-containing food products during exercise stimulate the mTORC1 pathway, increasing muscle protein synthesis and decreased whole-body proteolysis
*recommended leucine intake is currently 14 mg·kg−1·d−1, but the amount required to maximize the stimulation of muscle anabolic intracellular signaling may be at least 40–65 mg·kg−1·d−1, and even up to 7–12 g·d−1 to contribute to the preservation of muscle mass during stressors such as energy restriction
*leucine, and perhaps the remaining BCAAs, may have the ability to directly influence muscle protein breakdown