Dieters have a fixed target in mind for their maximum daily calories, and when they exceed it for some unexpected reason, such as being given a pair of large milkshakes in an experiment, they regard their diet as blown for the day. That day is therefore mentally classified as a failure, regardless of what else happens. Virtue cannot resume until tomorrow. So they think, What the hell, I might as well enjoy myself today—and the resulting binge often puts on far more weight than the original lapse. It’s not rational, but dieters don’t even seem to be aware of how much damage these binges do,
