First there is a story about lemonade fast and ulcers. That fast was originally used to cure ulcers. Walking is good for cardiovascular health but many have died of a heart attack while walking and sleeping. So that means that sleeping and walking are dangerous activities that can kill you so you should avoid both.
Fasting is a great way to quit smoking. You lose some muscle mass while fasting but everday you are losing some muscle mass and gaining other muscle mass. In 7 years, none of the muscle mass you have now will be left. After a few days of fasting your body goes into ketosis and burns fat.
The muscle you lose will be the most diseased and poorly formed in your body since that is what the fasting body likes to consume. If you have a lot and it is a danger, the body will decide to consume it instead of fat. Fasting is known a God or nature's bloodless operating table. When the fast is over you will gain the muscle back easily since the body has increased assimilation abilities after a fast. I forget the name but a champion bodybuildler fasts and wrote an article for it in one of the muscle mags.
As far as better assimilation, consider this. You need to get some work done but you are getting tired of doing it. So instead of pushing your self, you take and nap or get a good night sleep and then you can do the work better.
Fasting gives your body and digestive system a well needed vacation and after it works much better.