2) Lifting while your body is in a “fed” state may decrease your workout performance.
Digestion, like any other body process, takes a bunch of energy. Think about how you felt immediately after Thanksgiving dinner: tired, gluggy, or comatose are all probably apt descriptors. That’s because your body was diverting energy to the digestion process, thereby reducing available energy for your other body functions.
Sure, not every meal is as extreme as this. But a similar competition for energy goes on all the time. Because of that, saving more of your eating for after your workout may actually leave you with more energy than if you had a preworkout meal, and it may even be better for building muscle.