1. Percentage vs. Total

You actually tap into the greatest amount of fat while sleeping and at rest. This doesn’t mean it’s the largest fat-burning activity, but it is important to know that with more exertion your total % declines

2. Energy Systems

One of the reasons your body burns less fat as a fuel source the harder your workout or the more stressed you are is due to the fact that it can’t convert it fastest enough to usable energy. In these cases, glucose, lactic acid, or creatine phosphate is used. 

3. Become Fat Adapted For Real

The goal is being fat-adapted simply means being able to properly use fat or glucose for energy anytime your body needs it based on the energy system required to do the work at that moment.