It’s said that the average person can gain between 7 and 10 pounds during the period between Thanksgiving and New Year’s. But if you’ve been justifying that based on the notion of “ego depletion,” meaning that your willpower is limited so you’re using it to focus on work instead, you’re out of luck: The notion has been disproven.

Ego depletion was based on a number of scientific studies indicating that people had a finite amount of willpower, and if they were using it on things like choosing to eat radishes instead of chocolate chip cookies, they would then have less willpower available for things like choosing to do work rather than playing Neko Atsume.

That concept allowed any number of us to rationalize why we were eating junk food, or not exercising, or any of the other things we felt like we should be doing. After all, we only had so much willpower to go around, right?

“For more than 15 years, psychologists believed the answer to that question was clearly yes,” writes Stephanie Pappas in Mashable. “Indeed, a whole line of research, based on a seminal study published in 1998, suggested that not only is human willpower a depletable resource, but it’s also drawn from a singular source in the brain. Hold back from scarfing down a chocolate chip cookie, and you’ll be less persistent at logic puzzles. Refrain from expressing your emotions, and math problems will seem so much more painful.”

Ego depletion was disproven when people went back and looked at the studies and realized that they were too small to be used as the basis for such sweeping generalizations. “The 2015 meta-analysis, though, found that the research literature on ego depletion was chock-full of studies that had small sample sizes with large effects and virtually zero small sample sizes showing no effect,” Pappas writes. “It was a red flag for publication bias: Journals don’t typically want to publish studies that find that two things aren’t related. Thus, studies that do find relationships, even by chance, are more likely to be published.”

Researchers then went back to try to reproduce the original studies’ findings and failed to do so, Pappas continues. That’s not to say, of course, that ego depletion isn’t a thing; simply that it isn’t yet reproducible through scientific studies.

There is, of course, a larger lesson to be drawn from all this. (Isn’t there always?) Like the “Rule of 48” in The Andromeda Strain—where one group of scientists discovers that humans have 46 chromosomes, not 48, and the scientists go back to the old pictures and realize that they all show 46 chromosomes, too—it’s easy to get caught up in groupthink and wishful thinking (not to mention confirmation bias). It sounds right that we have only so much willpower to go around. It has, as the phrase went a few years ago, “truthiness.”

It’s a good idea, therefore, when someone makes a pronouncement at work that sounds too good to be true because it fits so neatly into preconceived notions, to check these things out. It’s not always easy to go against the prevailing wisdom. But there’s times when, as the saying goes, that what gets us into trouble isn’t what we don’t know, but what we do think we know that ain’t so.

(Incidentally, just as a QED, that quote is often attributed to Will Rogers and Mark Twain. Ain’t so; it’s 19th-century humorist Josh Billings.)

And by the way, the 7-10 pound weight gain is another misnomer. According to the New York Times, it’s more like one pound. So whether you choose to use your willpower or not, have a good Thanksgiving.



