Just going through basic nutrition books to get a better handle on things before school starts back up for the first time in 4 years and came across something I guess I knew but actually hit me this time around. At rest, 25% of the blood leaving the heart is responsible for taking care of the digestive system. A pretty significant amount. When working out, 85% or more goes to the muscles. Is this elementary nutrition fact a big part of why fasted nutrition workouts are great? Increased blood flow to the muscles that's available because it isn't needed for digestion? Just something cool I thought I'd throw out there. Feel free to cast me down and call me a noob if this has been said before or is too poorly worded to understand!
Interesting question! I'm no expert, but logically I think the blood flow idea makes a lot of sense. Also, if someone eats and then works out, blood sugar levels are higher, and that is the energy used first. I may be wrong, but it seems reasonable to me that working out while fasting means that the body has to go elsewhere for the energy for the workout, including fat stores, and thus sends the fat supplies to the muscles for the energy to burn.
Like I said though, I'm no expert. If someone has a more informed answer, I would also like to hear it!
Its perhaps part of the goodness. Other part is that as you have no food in stomach, you must burn your fat and that practices your beta oxidation pathways. Metabolic flexibility is very important.