86Thousand400: Stress and Fat

Cortisol wears a number of different hats during the stress response, one of which is that of traffic cop for metabolism.

Cortisol takes over from epinephrine and signals the liver to make more glucose available in the bloodstream, while at the same time blocking insulin receptors at non essential tissues and organs and shutting down certain intersections so the fuel flows only to areas important to fight-or-flight. (This is a stress response).

The strategy is to make the body insulin-resistant so the brain has enough glucose and can focus/attention on the challenge.

Cortisol also begins restocking the shelves, so to speak, replenishing energy stores depleted by the action of epinephrine. It converts protein into glycogen and begins the process of storing fat. (This is dangerous if we worry unnecessarily). Worry = Fat storage..! (But don't worry)!

If this process continues unabated, as in chronic stress the action of cortisol amasses a surplus fuel supply around the abdomen in the form of belly fat. (Unrelenting cortisol also explains why some marathon runners carry a slight paunch despite all their training - their bodies never get the chance to adequately recover).

The problem with our inherited stress response is that it mobilizes energy stores that don't get used.

The brain is a conspicuous consumer of glucose, using 20% of the available fuel even though it accounts for only 3% of our body weight. But it has no capacity to store fuel, so cortisol's role in providing a steady flow of glucose is critical to proper brain function.

Operating on a fixed budget of fuel, the brain has evolved to shift energy resources as necessary, meaning that mental processing is competitive. It's simply not possible to have all our neurons firing at once, so if one structure is active, it must come at the expense of another.

One of the problems with chronic stress is that if the HPA axis is guzzling all the fuel to keep the system on alert, the thinking parts of the brain are being robbed of energy. (Stress doesn’t allow you to step back and think clearly, however exercise can help to alleviate stress).

Constantly high levels of cortisol - due to chronic stress - make it hard to learn new material, and why people who are depressed have trouble learning. Excess cortisol can also block access to existing memories.

Cortisol is of course extremely important to the body, however past a certain point it becomes detrimental. The combination of exercise and avoiding stress means that less cortisol is released unnecessarily which in turn means more focus can be placed on the important things in your life and also less fat is made by unwanted cortisol responses.