5 Reasons You should ALWAYS Workout During a Fast [Burn more fat]

Studies are starting to demonstrate the benefits of such training. For example, one study looked at muscle fibres both before and after training in the fasted state. This means that you fast for a certain period of time, usually around 24 hours, and then do your endurance or other training. The combination of low insulin and high adrenalin levels created by the fasted state stimulates adipose tissue lipolysis (breakdown of fat) and peripheral fat oxidation (burning of fat for energy).
Other studies had already shown that the breakdown of intramyocellular lipids (IMCL – fat inside the muscle) is increased by training in the fasted state. Six weeks of training in the fasted state also induced a greater increase of fatty acid binding protein and uncoupling-protein-3 content in muscle.
https://www.dietdoctor.com/fasting-and-exercise