Do you snack more in the evening because your will power is worn out?

Is eating late at night bad for you?

Lots of people think so though studies show it doesn’t really matter when you eat. If you are a fan of breakfast, eat breakfast. If you’d rather eat a big meal late in the day, go ahead. The real issue isn’t when we eat, it’s what we eat.

The problem isn’t with night eating per se. It’s more about night time food choices. It’s at night when we tend to eat calorie dense foods that are high in fat and sugar.

Most of us make bad food choices in the evening. But why? It’s the explanation I’m interested in. The familiar story is all about ego depletion, the widely view that will power and ethical self control is a limited resource. Here’s the Wikipedia version, “Ego depletion refers to the idea that self-control or willpower draw upon a limited pool of mental resources that can be used up.”

If you’ve ever met with a personal trainer or nutritionist who talked about evening snacking that’s likely the explanation they gave. Pretty much everyone eats healthily at breakfast, lunch is usually pretty good, dinner just okay, but by the time night time comes around it’s all potato chips and ice cream into the night. Nothing good is eaten in the evening. Why? Well, again the theory is that we started the day all full of will power and good intentions. But by the end of the day we’re tired. Our will power is worn out.

Bring on the Pringles!

Late night Lucky Charms!

Ego depletion theory is also the explanation people give for making healthy eating choices into habits. The more you try to do things with sheer grit, the harder they are, and the more worn out you get. It’s tough having cookies in the house and not eating them. You’re using up your will power, a limited resource. Better just to have the habit of not keeping cookies in the house.

People also tell this story when they say you should go the gym in the morning. By night time, you’ll have used up all your will power and gumption at work and ego depletion explains why we find it harder and harder to do the things we know we ought to do as the day progresses.

Sounds good, right?

Okay but what if ego depletion theory is all wrong?

See Everything Is Crumbling: An influential psychological theory, borne out in hundreds of experiments, may have just been debunked. How can so many scientists have been so wrong?.

A paper now in press, and due to publish next month in the journal Perspectives on Psychological Science, describes a massive effort to reproduce the main effect that underlies this work. Comprising more than 2,000 subjects tested at two-dozen different labs on several continents, the study found exactly nothing. A zero-effect for ego depletion: No sign that the human will works as it’s been described, or that these hundreds of studies amount to very much at all.

This isn’t the first time that an idea in psychology has been challenged—not by a long shot. A “reproducibility crisis” in psychology, and in many other fields, has now been well-established. A study out last summer tried to replicate 100 psychology experiments one-for-one and found that just 40 percent of those replications were successful. A critique of that study just appeared last week, claiming that the original authors made statistical errors—but that critique has itself been attacked formisconstruing facts, ignoring evidence, and indulging in some wishful thinking.

For scientists and science journalists, this back and forth is worrying. We’d like to think that a published study has more than even odds of being true. The new study of ego depletion has much higher stakes: Instead of warning us that any single piece of research might be unreliable, the new paper casts a shadow on a fully-formedresearch literature. Or, to put it another way: It takes aim not at the single paper but at the Big Idea.

Baumeister’s theory of willpower, and his clever means of testing it, have been borne out again and again in empirical studies. The effect has been recreated in hundreds of different ways, and the underlying concept has been verified via meta-analysis. It’s not some crazy new idea, wobbling on a pile of flimsy data; it’s a sturdy edifice of knowledge, built over many years from solid bricks.

And yet, it now appears that ego depletion could be completely bogus, that its foundation might be made of rotted-out materials. That means an entire field of study—and significant portions of certain scientists’ careers—could be resting on a false premise. If something this well-established could fall apart, then what’s next? That’s not just worrying. It’s terrifying.

Also, Maybe You Have Unlimited Willpower.

These are issues for psychologists to sort out among themselves. But for you, it may not even really matter that much whether ego depletion is “real” or not. What matters is how you think about your own amount of willpower. A very intriguing direction of research is finding the power of a person’s own beliefs about willpower may be what makes the difference here. When people believe their willpower is limitless, they’re more likely to go after personal goals, they’re less likely to burn out, and they’re happier. In a sense, when people believe their willpower is limitless, it turns out to betrue.