[venomsnake]

Caloric surplus is meaningless. You are not a 4 phase combustion engine.

A lot of foodstuff a person ingests get used for other things - building, repairing tissue, making proteins and all other stuff that people need to be alive except oxidation for fuel.

[eru]

That's why it's a surplus. You need a few calories just to stay alive and not slim, and that inclused repairing tissues etc.