Do you fuel for the work out properly?
Many people prefer training on empty stomach, while some like to eat before. Generally speaking everyone is different and should do what ever they feel it works best for them.
Sometimes we do things only because of the habit. People that didn't eat before work out in years might find very difficult to begin with the pre work out meal, but doing so might prevent muscle loss, increase performance & recovery.
Other then fasted low intensity cardio in the morning, there's not much benefit from training on empty stomach.
Stored body fat is simply not body's preferred energy source and we get most of energy for work out from the food that we ate. Unless there is enough adequate fuel from food, before burning stored body fat we are most likely going to break down muscle tissue and use it as a source of energy.
Again, it all depends on type of training, personal fitness level and eating pattern but most of the time this is the case.
Pre work out meal, depending on the quantity and as well as what is it made of should be eaten at least 2 hour before work out.
Small snacks such as energy balls could be eaten about 45mins before or piece of fruit 15-30mins before the work out as fructose is absorbed quickly.
For longer training sessions, that are lasting 2-3 or more hours, it's important to keep fueling throughout.
For my long bike ride I like to take 1 homemade energy ball + 2 gels per hour. I prefer some protein & fat during ride other then just carb from gel as it will prevent sugar spike & drop and give me more lasting energy.
DM for recipe.