It’s about the size of a sugarlump, and hidden deep inside your skull. Every so often it has you reaching for the cookie jar, your secret stash of crisps, or the cheese compartment of your fridge.
The hypothalamus is the region of your brain that protects you from starvation. It measures fat, sugar and other nutrients in your blood, and makes you feel hungry when they start running short. It tells you to eat.
Another part of your brain, the prefrontal cortex, will tell you to have an apple instead, because it’s good for you. But if this common-sense part of the brain fails to persuade you, you’ll be nibbling on a bar of hazelnut chocolate in no time. This calorie-packed treat helps you build fat, which is exactly what your hypothalamus wants: it’s trying to prepare you for a harsh winter in your draughty cave.
So if you want to lose weight, get your hypothalamus under control. That’s the message of pediatricians Felix Kreier and Maarten Biezefeld, who’ve written a book entitled De hamster in je brein. It’s more of a self-help title than a dieting guide: instead of nutritional advice, it’s full of scientifically proven ways of fooling your brain, like using a smaller plate because it makes you think you’re eating more. There’s all sorts of interesting stuff about what goes on inside your head: for example the hypothalamus also governs breathing, body temperature, and reproduction. And even worms have a primitive version.
Kreier and Biezeveld are in a meeting room in OLVG Oost, the hospital where they met, coronaproofing themselves by sitting in opposite corners. Kreier did a doctorate at the Netherlands Brain Institute on how different regions of that organ affect excess weight, and Biezeveld thought this was an interesting subject, so they decided to write a book together. Its slogan: ‘Read this before you ever start dieting (again)’.
If you know how your brain works, Kreier says, you’ll understand why it’s so incredibly hard to stick to a diet. ‘Once you realise that the brain consists of different parts, and they’re sometimes at loggerheads with one another, you understand why it’s such a struggle. And that’s a relief.’
Of course the brain is incredibly complex, but the two doctors say it boils down to this. The hypothalamus makes sure you get enough to eat, and if you don’t, it gets stressed and tries very hard to make you do so.
Kreier and Biezeveld call the hypothalamus ‘the hamster’. But two other regions of your brain also affect your weight. One is the prefrontal cortex, which they refer to as ‘the decision maker’, and which solves problems, learns, and organises things. It’s your prefrontal cortex that makes the decision to lose weight in the first place.
And then there’s the limbic system, the ‘lobbyist’, which gives you a good feeling when you eat.
If your prefrontal cortex remains in control, you should have no problem losing weight. Every time your hamster tells you to eat, your prefrontal cortex will decide whether that’s the right thing to do, and as long as it’s wholly focused on weight loss, all well and good. But if it’s distracted, for example by the thought that your tax return is overdue, you may well end up reaching for the waffle mix.
You can’t rely too much on the limbic system either. Eat a salad, and it will make you feel good for doing the right thing. Eat a Big Mac, and it will make you feel good because it was delicious.
Kreier says it all comes down to this: ‘Your body listens to whichever part of your brain shouts the loudest.’
So the art lies in fooling your brain, training it just as you’d train your muscles. There are all sorts of tricks you can use. Choose low-calorie foods that make you feel sated. Distribute meals evenly through the day and eat healthy snacks in between. If you get this right the hamster may feel hungry, but it won’t get stressed.
Here’s another tip: do your own cooking. The act of buying, chopping and preparing the ingredients puts your hypothalamus in eating mode, and helps you to feel full sooner. And give your food the attention it deserves: don’t just put it on a tray on your lap and wolf it down while you watch TV.
If you do feel peckish between meals, get some exercise. Your hypothalamus will leave you in peace if you’re on the move – after all, you may be hunting down your next meal, and you don’t want to be distracted by a rumbling stomach.
Don’t lose weight too fast
It’s also important to get a good night’s sleep. Too little will put the hunger and satiety hormones out of whack, and the hamster will pay less attention to signals that you’ve had enough to eat.
Don’t be afraid to ask others for help: family and friends can provide valuable moral support to help you keep going. If you’re following the hamster method, you can sign up for an online programme of daily exercises to get the three parts of your brain working harmoniously together.
But perhaps the most important message is not to lose weight too quickly – 200 grams a week is quite enough. ‘That’s still ten kilos in a year,’ Biezeveld points out. ‘And it’s long-term weight loss.’
Shed weight too fast and the hamster will get stressed. ‘It sees that there’s very little coming in, you’re using up a lot of energy, and your reserves are dwindling,’ Kreier says. ‘So it thinks you’re dying, and does everything it can to stop this happening. It slows down your heartbeat and metabolism, and reduces your temperature.’
Basically, it puts your whole metabolic system into economy mode. If you want to lose a few kilos, you have to eat even less and exercise even more, and there’s a strong chance that you’ll lose momentum and regain weight, setting up a yoyo effect. This can be bad news, as your hypothalamus may set your metabolism permanently in economy mode, so you gain weight even when eating normally.
‘So you should avoid crash diets,’ Biezeveld warns. ‘You may be able to fit into your swimsuit again after four weeks, but you haven’t learned a new routine and lifestyle that you can maintain forever.’