Substrates for MPS: Carbs vs. Fats

[AdamWW]

I'm curious if the energy substrates that fuel MPS activity have ever been analyzed.

Not in terms of training fuel, as it appears explosive movements are clearly reliant on primarily glucose, but when it comes to the post-training MPS (which lasts for hours - several days after), is there a biological preference in terms of glucose vs. fat oxidation when we actually synthesize new tissue?

For example, in acute energy deficit, is muscle-building primarily relying on triglyceride liberated from stored adipose? Or, is it still utilizing glucose? Both? Is one preferential over another, or does it not matter?

I'm especially curious in the energy deficit and also KETO or very low carb scenario when dietary glucose is low/nothing; does the reliance on stored fat to fuel post-training hypertrophy offer the same results as someone consuming more carbs?