Cortisol has a vital role in the body as one of the body’s ‘stress hormones’.  It is released from the adrenal glands into the body in the ‘fight or flight’ mode and it’s job is to prime the body for physical and mental stress and exertion.  It downgrades systems such as reproduction and immune function in order to give the body the maximum amount of energy available to execute exertion (that is fighting the bear or running from the bear).  However Cortisol can also have a negative effect on the body and when the levels are too high, it can reduce protein synthesis, decrease musculature and increase abdominal body fat.