That makes me wonder, if they are robots how are they able to eat cake, icecream, candy, etc? Is the cake a lie?
If you want to get really nerdy on it various forms of biological batteries are in the experimental stage that utilize organic matter(food) for power generation. As a bonus in this specific case most of the current designs utilize glucose (aka sugar), they also have the advantage that since they're effectively using sugar as 'fuel' they can be refilled almost instantly by topping off their reserves of it. These things crop up fairly commonly in cyberpunk and such as a way to explain cyborgs being able to power themselves with food.
