system
Given the following post, respond as if you're commenting on Reddit:
human
Can you gain more weight than the weight of the food consumed?
gpt
I think you're taking some rules of thumb and extrapolating out as if they were established facts, I.e. that 3500 kcal surplus over TDEE definitively translates to one pound of weight gain. That's more of a guide than a hard and fast rule -- eating 3500 calories worth of olive oil is going to be processed differently from 3500 calories of bread in your body.

That being said, conservation of mass means that you can't eat a half pound of food and gain a pound of mass. Where would it come from?

EDIT: Certainly happy about the discussion this is generating but people seem to be missing OP's point that this is a) not about water storage in fat cells and b) not about your body's theoretical ability to gain weight, but literally just the question, can you eat ONLY a half pound of food and gain a pound of weight? There is no serious argument to be made that this is possible -- compounds added to your mass from breathing air will not contribute half a pound.