Quick answer to the topic is No. The human body is an amazing thing. It has formed, and adapted for centuries to what seems to be the finished product of today. Is there a next step? Will we continue to evolve? Both interesting questions I cant wait to find the answer out to. Back to muscle wasting. The body has multiple sources of energy. The first source of energy is the energy we consume. Anything and everything we eat either gets utilized or stored. When the body is not fed enough energy it seeks out its second source. Stored energy. We have a few sources of stored energy. The first two lines of stored energy is fat and glycogen storage's. These sources require the least energy to remove and utilize as energy. Once both of those have been completely depleted and we are retaining no more body fat. All we have left on us is muscle and organ tissue and we continue to keep our body in a caloric deficit, survival instincts kick in and the body is required to eat away at muscle to drop out resting metabolism. The amount of muscle that is wasted is based on the significance, and the period of the deficit. The bigger and longer the deficit the more muscle that is wasted. A rough guess is that our metabolism will rise or fall approximately 50 calories for every lb of lbm. So next time you forget your protein shake post work out its cool bro you got time.