What if you could lose weight just by sitting around thinking, finding the square roots of stuff in your head, considering the use of negative space in the art of Matisse, or coming up with a Grand Unified Theory of particle physics? That would be not so bad. I mean, if I had to choose, I would rather think hard than work hard. And the fact is, you actually do burn calories by thinking. Just not a lot. I mean you’re not going to be able to think away that bag of Doritos. It’s just not going to happen. As we’ve mentioned before, your brain is voracious in its hunger for energy: At least 10 to 20 percent of the calories that your body uses when it’s at rest is taken up by your brain.
You might be, like, picturing the inside of your brain and think, “Yeah, all my neurons are using all that electricity to communicate.” But it’s not like your brain’s circuits are buzzing with streams of electrons like your computer or phone is. Instead, your neurons communicate with each other in a number of different ways. One is using chemical signals called neurotransmitters, and much of the energy that thinking demands actually goes into producing and releasing those chemicals. So, how much energy are we talking about? Well, at rest, the best estimates are that your entire brain uses about a fifth of a calorie per minute. But can you burn more calories by thinking harder? Well, scientists have actually tried to measure that. A couple of experiments conducted in Britain, for example, found that levels of blood glucose dropped when people were asked to perform intellectually challenging tasks, like solving puzzles, compared to those who did simple, you might say, mindless tasks, like pressing a button repeatedly. Plus, brain scans of subjects who were asked to do some serious thinking, like doing multiplication problems in their head, showed an increase in glucose uptake directly to the brain. But it wasn’t, like, a ton of difference.
Research suggests that when you’re consciously chugging away as hard as you can, your brain might consume, like, 1.5 calories per minute. So, an extra calorie, maybe a calorie and a quarter, more than you would at rest. Considering that your brain really only deliberates seriously about things for a couple minutes at a time, most estimates are that you burn anywhere from 10 to 50 calories a day from the act of thinking. So thinking, yes, it burns calories, but probably not enough to be super significant. But really? Is that why you’re thinking anyway?