Iirc chunks of meat weigh between half a pound and a single pound in game. Which, depending on the animal, would put it in that caloric range.
For example, a pound of rabbit is about 500cal. So the “cooked meat” in game is definitely a solid rough approximation.
The point does remain though that in one sitting the PC can definitely eat way more than the human stomach could conceivably hold. I don’t know how one would fix it without completely reworking hunger and starvation though.