low_delta

Here's an excerpt from Michael Pollen's book, In Defense of Food.

"Eat Less" is easier said then done, however, particularly in a culture of cheap and abundant calories with no deeply rooted set of rules to curb overeating. But other cultures do have such rules and we can try to emulate them. The French have their modest portions and taboo against seconds. The people of Okinawa, one of the longest-lived and healthiest populations in the world, practice a principle they call hara hachi bu: Eat until you are 80 percent full.

This is a sensible idea, but also easier said than done: How in the world do you know when you're 80 percent full? You'd need to be in closer touch with your senses than many Americans at the table have become. As Rozin and other psychologists have demonstrated, American typically eat not until they're full (and certainly not until they're 80 percent full), but rather until they receive some visual cue from their environment that it's time to stop: the bowl or the package is empty, the plate is clean, or the TV show is over. Brian Wansink, a Cornell professor of marketing and nutritional science who as done several ingenious studies on portion size and appetite, concludes that Americans pay much more attention to external than to internal clues about satiety.* By comparison, the French, who seem to attend more closely to all the sensual dimensions of eating, also pay more attention to the internal cues telling them they feel full.

*In one study, Wansink rigged up bowls of soup in a restaurant so they would automatically refill from the bottom; those given the bottomless bowl ate 73 percent more soup than the subjects eating form an ordinary bowl; several ate as much as a quart. When one of those hearty eaters was asked his opinion of the soup he said, "it's pretty good and it's pretty filling." Indeed.

At some point in the recent past, I realized the amount I was eating was often based on the amount I usually ate. I'd take a portion that I though was reasonable, and then go back for a little bit of seconds. I thought I needed to eat until I was full, but if I didn't go back for seconds, I was still full.