There's someone in the friend group who, going by the last calculation, sat right around a BMI of 18.5, yes, aware of all the issues with that metric, but useful enough for this conversation. He's the type who'll leave the final bite of cake sitting there once satisfied, or skip the last piece of chicken entirely.
Never understood that behavior before. Completely get it now.
A couple weeks into MJ, he told me 'oh, so this is just how I feel constantly.' Yes. Exactly that. And it's genuinely wonderful.