mTOR will make you bigger: The mTOR pathway is a central regulator of metabolism with important roles in the function of tissues including liver, muscle, white and brown adipose tissue, and the brain. The activation of TORC1 activation is required for myofibrillar muscle protein synthesis and skeletal muscle hypertrophy in humans in response to both physical exercise and ingestion of certain amino acids or amino acid derivatives. Here is a very good lecture by David Sabatini about the regulation