My FIL was a hearty eater.
We were out with him and MIL one time and he ordered the "all you can eat" crab legs. Not a buffet, but a served meal place.
Round one -regular serving.
Round two - regular service.
Round three - a scanty plate of crab leg bits and pieces.
FIL started to complain. MIL took his hand and quietly said "they're saying you've had enough dear, I agree."
End of discussion.