Can you lose weight just by *thinking*?

Your brain uses a lot of energy to think. So, if you think more, or harder, you'll burn more calories, and logically end up losing weight, right? Unfortunately, it's not that simple.

Photo by Craig Adderley

The brain is the most energy-demanding organ, by some margin. It makes up about 2% of the weight of your standard human body, but consumes 20% of said body’s readily available calories.

But if the brain burns so many calories just through everyday use, then, logically if you use it more, by thinking or concentrating really hard, and thus producing more brain activity, wouldn’t it burn even more calories?

And because burning calories leads to weight loss, shouldn’t you be able to lose weight by simply… thinking more?

This was actually a proposition put forward during in an interaction between Steph Garrero and Mike Bubbins on the latest episode¹ of their podcast (with Elis James), the Socially Distant Sports Bar.

In fairness, they weren’t saying “this will definitely happen”, but rather “would this happen?”

As I listened, I realised this notion honestly hadn’t occurred to me before. The same can presumably be said for many others. But then, they presumably haven’t been studying the brain for 20+ years, unlike some people.

So, can you lose weight just by thinking harder, and using your brain more?

Well… no. ²

In fairness, this shouldn’t be a revelation. For instance, one route to constant, intense brain usage is playing video games. However, with the best will in the world to anyone who finds joy in their interests and enthusiasms in the modern world, the physical stereotype attached to die-hard gamers isn’t exactly ‘svelte athletes’.

So, using your brain more doesn’t burn more calories, or cause you to lose weight.

But.. why not?

Photo by Markus Spiske

Brain Fuel

Let’s make one thing clear; when people talk about “losing weight”, they invariably mean “losing fat”. If they put on several kilos of pure muscle mass, they wouldn’t be devastated.

No, we as a society have decided that visible, excess fat (i.e. adipose tissue) is unsightly, unpleasant, unhealthy, and often a sign of moral weakness.

While pretty much all that is wrong, in various ways, the consensus remains that too much body fat is bad, and should be dealt with. Hence gyms and diets are so common, and widespread.

We can debate the problems with demonising fat at length, but the key point here is, no, you can’t get rid of fat by upping the use of your brain.

Yes, fat is an energy store. But it’s not the go-to source of energy for the body. It’s glucose, which carbohydrates are broken down to, that provides the primary energy source for all the body’s organs. Sugar, basically.

The body typically maintains a viable level of glucose through the complex use of digestion, liver functions, storage mechanisms, hormones like insulin, and so on.

And your body usually keeps enough glucose on standby to ensure everything remains running. These stores are replenished through diet (eating sugars and carbs). But, if your body remains active for longer than glucose stores last, and you don’t consume more sugar in response, your body needs to use alternative fuel sources.

That’s when it starts breaking down your body fat, to release the energy contained therein. That’s why sustained exercise and bigger muscles (which use more energy) eliminate fat.

However, the brain is much ‘fussier’ than other organs. It only wants glucose. And because it’s, you know, the brain, it typically gets what it wants. So, the body has many painfully complex physiological mechanisms ensure the brain gets its precious glucose³.

Although, the brain technically can run on fat, or fat-derived molecules, as it can also run on ketones, the body’s backup fuel during periods of prolonged fasting or starvation. Interestingly, some evidence suggests that the brain runs better on ketones, and they help protect and repair brain function following brain injury/disease⁴.

So, why doesn’t the brain run on ketones all the time?

Maybe because they’re harder to obtain (they’re synthesised by the liver from fat molecules) than glucose (readily obtained via diet)? Honestly, if you’ve got an issue, take it up with evolution!

But the point remains that the brain only switches to running on ketones (fat) after (very) long periods of dietary restriction. But even then, the brain still needs some glucose to function. It can’t survive on zero glucose. And the starved body meets this demand by creating new glucose, via an internal process which involves breaking down amino acids.

Which are usually obtained via muscle protein.

What I’m saying is, the body will start to break down muscle before it deprives the brain of sugar.

So, no matter how much extra thinking you do, your brain won’t be burning fat to do it. You’ll need to get to a state of advanced starvation for it such a thing to even be feasible.

And if you are in that state, ‘weight loss’ is presumably no longer a priority.

Image by Pixabay

The brain’s going flat out

Even if your brain could somehow easily use fat as a fuel source, this still wouldn’t help. Because the whole premise of “Does thinking more help you lose weight?” is based on the notion that we can just choose to use our brain ‘more’.

The brain is often likened to a muscle, but if you’re arm is dangling loosely by your side one minute and curling a 50kg dumbbell the next, there’s a stark difference in how much effort and energy is being used by the muscles of that arm.

But that’s not how the brain works. If you’re not thinking about anything in particular, then suddenly start focussing and analysing something intensely, there’s barely any difference in how much energy your brain is using.

Because your brain is active all the time. Just keeping you alive and conscious and aware at all is herculean task, on the physiological level.

The brain has also spent millions of years evolving to be as ruthlessly efficient as possible, in terms of energy consumed and computation achieved. And part of this involves a precise balance between how much dense brain tissue can be packed into the skull while still allowing room for the blood vessels etc. that provide the fuel supply.

This means the basic brain is already operating at it’s biological limits. Meaning it’s actually pretty hard to increase the amount of work the brain is doing. You can only really change the type of activity it’s producing, by shifting resources around. You can’t make the car go faster when the accelerator is already touching the floor. All you can do is steer it.

And even when we do manage to ‘boost’ the activity of the brain (because there’s always a bit of wiggle room), the energy consumption increases by about 5%, at most. Which doesn’t add up to much. Sticking with the car comparison, it’s like driving at 70mph on the motorway and opting to nudge it up to 72mph. You might technically get there quicker, but not in any way that’ll make a significant difference.

Ultimately, the brain is a terrifyingly complex organ capable of many great things. But “fat burning” isn’t one of them.

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You can still stimulate and enhance you brain in other ways, by buying one of my books. Or reading, sharing and/or subscribing to this blog!

1. Episode 248: “Sparky’s Thighs”

2. I know, I know, ‘paging Mr Betteridge’, and so on.

3. The issues with insulin that result in diabetes can throw these out of whack, which is why poorly-managed diabetes can be so bad for brain function (e.g. diabetic coma).

4. This is also the basis for the ‘keto’ diet. If you cut sugar from your diet and only consume fat and protein, your body has to adapt and starts metabolising fat and producing ketones by default.