One of the many invaluable lessons in Taubes’s Good Calories, Bad Calories is that overeating is a myth. This makes a lot of sense. Suppose you “overeat”. Then, you won’t be as hungry at the next meal, so you’ll “undereat”, and the two meals will average out as “normal”. In fact, we all “overeat” during the day, and “undereat” while we sleep.
One of the main points that Taubes stresses is that hunger is a physiological, and not a psychological phenomenon. He discusses Edward Adolph’s rat feeding experiments from the ’40s which clearly showed that food consumption is regulated by caloric need, and not by volume, mass, or even taste! For example, when the rats’ food was diluted they kept eating until they got enough calories, even though they ate a much greater volume and mass of food. And when calories were directly injected into the rats’ stomachs, their intake dropped accordingly.
The implication is that trying to eat less by using tricks like drinking water or eating more fiber to create a sensation of fullness are futile. You’ll be hungry until you actually put real calories in there. (I should add that trying to eat less is a horrible way to lose fat: the cost is all the negative effects of semi-starvation and you generally regain all the fat when you return to normal eating.)
Hunger, and hence food consumption are hormone driven: we eat to get enough calories. Period. Just as children eat a lot because they’re growing, fat people “overeat” because they’re growing (fatter). In neither case are they growing because they’re overeating. Their bodies need more food in order to grow, so their appetites are correspondingly larger. When thin people “overeat”, they don’t get fat, they just aren’t as hungry for the following meal, at which they “undereat”. The bottom line is that you don’t control your hunger—your caloric need does—so you’ll end up eating the “right” amount over the long term.
(Incidentally, Taubes points out that, if our hunger weren’t regulated by caloric need, it would require a feat of incredible accuracy to maintain a constant weight over a period of several years. A few extra calories per day would add up to major fattening in the long term. Of course, that’s not what happens.)
The fact is, overeating is really quite rare—because it hurts. If you don’t feel sick, then you haven’t overeaten. For most people this happens maybe once or twice a year. If you ate a lot, but feel alright, that’s just calories in the bank which will delay your hunger. Eating big, nourishing meals is nothing to feel guilty about—you’re giving your body the calories it needs to function, and if it doesn’t need them right away, it won’t trigger your hunger as quickly.