“Cortisol” has become a buzz word among the sleep deprived, the overweight and the WebMD user. The adrenal glands produce this hormone as a response to stress. If your stress is immediate, as in “that car just cut me off and I almost died” or as it was for our ancestors, “a saber tooth tiger is chasing me,” cortisol functions as one of our “fight or flight” hormones.
Its job is to ensure you have plenty of food ready to fuel your actions, whether that is swerving to the other lane or outrunning a beast. But if your stress is long term, as in “my boss is insufferable” or as it was for our ancestors, “winter is coming,” cortisol functions to prepare us for a famine. Now, its job is to ensure there’s plenty of fuel available for the next few months because your stress is unlikely to go away anytime soon.
In both acute and chronic stress, cortisol counteracts insulin, whose job is to decrease blood sugar. However, when in a fight or flight situation, the cortisol stops this decrease. It recognizes the need for readily available sugar in the blood for fast action fuel. Insulin decreases blood sugar in part by having the muscles store it as intermediate fuel, glycogen. But when the stress is chronic, cortisol prevents insulin from working, and the sugar in the blood is stored as long term fuel, fat. This is what is needed to survive the continued stress of impending famine....