Dragon Nap.

Time for a nap. Dragons are Cold Blooded of course. and most of their food intake is saved for muscle activity only. They don't need to keep their body warm with thermogenic burn like mammals. In fact, they can warm themselves when they need to with their breath, a combustible gas easily ignited by a spark generated from the flint and stone in their gizzards.
But for now, that last knight should hold him over for a few days...