When the body detects that there is an energy shortfall, it will do several things:
- It will attempt to reduce the amount of energy it discretionarily expends, which will necessarily impact thyroid hormones, and ultimately, thermogenesis, which is quite expensive in terms of energy consumed. So, during a prolonged fast, expect cold hands and feet, and better make sure you have a heavier blanket.
- It will attempt to conserve blood glucose and to do this it needs all tissues that do not require glucose to stop trying absorb it from the blood. Luckily, GH inhibits the use of glucose by the muscle. But that leaves us in the position of having lost a source of energy for muscular activity. Doubly luckily, GH is lipolytic which increases FFA availability as an alternative energy substrate for the muscles. But what about those tissues that cannot use FFAs and resulting ketones for energy? For those tissues:
- It will attempt to produce new glucose via gluconeogenesis. In this case, the inputs to this process are amino acids, so the body will need to find a supplier for these that does not require food. Luckily, we carry large pools of amino acids in all of our proteinaceous tissues. The trick is to liberate them, and this we achieve via the action of cortisol. So, during the course of a fast, cortisol levels increase to ensure that we can rely on gluconeogenesis as a source of glucose.
All of this is to say that actually, GH and cortisol are acting synergistically to provide the body with adequate energy from internal sources.
The cortisol belly fat connection is a marketing ploy to attempt to sell you some particular pharmaceutical or herbal cocktail that presumes to fix it. This is very similar to what happened with cellulite, which is nothing more than subcutaneous fat, but if I can sell you the disease, cellulite, then I can sell you the cures: anti-cellulite creams, exercise programs, and magic bracelets.
I am extremely fond of my proteinaceous tissues, especially my muscles. If there were some way to direct my cortisol to take some protein out of my nose, to make it more petite and button like, that would be great. Unfortunately, it doesn't work like that, so I am extremely wary of pushing my system into a situation where it will start to cannibalize hard earned muscle to keep my silly brain alive. So now, we have a tradeoff. How much muscle am I willing to give up for less subcutaneous fat? Not very much, so I advocate keeping fasting in the range of 40 hours in accordance with my priorities. If you really want to burn more fat, fast longer, realizing that you will be sacrificing more muscle tissue along the way. I do not recommend that you do this, but, it is ultimately your reality, and your decision.