After I haven't eaten for hours and then eat, why do I feel warmth spread through my body?

When I’ve gone a while without eating and then eat, it feels like I can feel the food hitting my bloodstream. I get an unmistakeable flush of warmth radiating outward from my core through my limbs and head. I don’t get hot, just warm, and it feels kind of good, actually. I’m curious what specifically causes this effect, is it my body generating ATP? My metabolism kicking in? The warmth from the food I ingested?

For the record, I have no medical issues like diabetes, hypo-/hyperglycemia, etc.