When I'm out at family dinners, one of my relatives in particular eats so fast I can barely see her limbs moving.   I have a theory that the speed at which hams eat contributes to their inability to accurately recall how much they've eaten.  Like, the meal disappears too fast for it to be recorded in their walnut-sized brains.  The result is that they're largely unaware of just how much food they've shoved down their gullets.    I think it's one of the reasons you have 400 lbs Tubblrinas claiming they only eat 500 calories a day and still don't lose weight.  In reality, they only remember eating 500 of the 3500 calories they've actually eaten that day*.  That and the fact that (1) they can't do basic maths; and (2) they lie about their portion sizes.