Grain Brain Summary

1-Sentence-Summary: Grain Brain takes a look at the impact carbohydrates have on the structure and development of your brain, arriving at the conclusion that a diet high in fat, low in carbs and especially sugar, combined with fasting, lots of activity and more sleep could provide you with a much higher quality of life.

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Grain Brain Summary

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I hate 90% of all diet books. Any diet, which categorically eliminates any category of foods (or even whole nutrient groups), is imbalanced and doomed to fail, if you ask me. It just doesn’t work.

You see, the mistake most diet books make is assuming they can deliver a diet that works for everyone and making conclusions about what must be good solely based on what’s bad. Grain Brain does this too, so it wasn’t off to a good start with me. But I have to admit that in the end, David Perlmutter turns it around, by branching out, going beyond diets, and providing a full picture of what makes humans healthy or ill.

Omitting the fact that the book states that fruit juice is as bad as soda for your health, and that some of its hypotheses are flawed in the way that they can never be proven, this actually made a few good points.

Here are 3 lessons from Grain Brain to help you make healthier decisions:

  1. Cholesterol isn’t unhealthy because your body regulates it, depending on your intake.
  2. With the right diet, your body can possibly create more neurons, which makes you smarter.
  3. Sleep has a huge impact on leptin levels, which in turn control your hunger.

No grain, no gain – is that actually true? Let’s see if we can find out!

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Lesson 1: Your body regulates your cholesterol, depending on your intake, so cholesterol itself isn’t a problem.

My grandma used to say: “Don’t eat more than one egg per day, it’s bad for your cholesterol,” when I was a kid. I distinctly remember having one boiled egg every Sunday morning for breakfast, and that was it. High cholesterol had been linked to lots of incidents of heart diseases for decades – but as it turns out, cholesterol isn’t the problem.

It’s the kinds of cholesterol and their ratio. You have two types of cholesterol in your body. They’re called LDL and HDL. LDL stands for low-density lipoprotein, while HDL equates to high-density lipoprotein. You can remember it by thinking of the L as low-quality and the H as high-quality, because LDL is the “bad” cholesterol, while HDL is the “good” cholesterol.

The total number of these two values combined + 20% of your triglycerides (a type of fat in your bloodstream) was always to be kept below 200 to avoid increased risk of heart disease. Actually, doctors now know that the ratio of HDL compared to your total is more important. Dividing your total cholesterol, say 150, by your HDL, say 50, should never yield a number higher than 5, and ideally stay at 3.5 or below.

However, eating lots of eggs, cheese or butter won’t hurt you in this regard. Only eating low-quality eggs, cheese and butter will, because of the other health-threatening ingredients they contain.

Your body regulates your cholesterol on how much you take in with your food. If you eat 5 eggs every day, your body simply produces less. Only if you completely overload (or lack) cholesterol will your body try to dial back (or overcompensate) – and that’s what causes problems.

If our ancestors survived on a diet that was 70% fats, chances are, so can we.

Lesson 2: You might get smarter by eating right, because it could allow your brain to create more neurons.

This is a classic example of a book blowing the results of a study out of proportion. When your brain creates new neurons, this process is called neurogenesis. An important part of this process is BDNF – brain-derived neurotrophic factor protein. The book states that by eating less, you can increase the amount of BDNF your brain produces, and therefore get it to create more neurons.

There are currently no studies out there that prove this effect in humans. So far, this has only been observed in diabetic mice and other animals, but not in humans.

The study the book quotes is indeed one about calorie restriction in elderly people, but this is confirmed to only positively impact memory, not BDNF.

What does that mean? There’s a chance that with the right diet (if you find it), you could get your brain to create more of those precious neurons – but so far, we don’t know.

Lesson 3: How much you sleep affects your leptin levels, which in turn control your hunger.

Here’s something we know for sure makes your life better: sleep more. A lack of sleep impacts the functionality of up to 711 of your genes, including the ones in charge of stress, inflammation, your metabolism and immune system.

Take leptin, for example, which regulates your body’s inflammation response to potential dangers. The level of this hormone influences how hungry you are and if you crave carbs. When leptin drops by 20%, your appetite and craving for carbs goes up by 24%.

What causes leptin to drop? Sleep deprivation. The less you sleep, the hungrier you’ll be and the more sugary foods you’ll crave, to make up for the lack of energy, and the harder it’ll be to resist. Sleep is also the only thing that impacts leptin levels – there aren’t any supplements for it.

You see, it’s all connected, and there’s no way to change your diet without impacting other things and vice versa. Don’t live a half-healthy life. So go get some rest and you’ll see your hunger will take care of itself.

Grain Brain Review

As I said, I was very skeptical about Grain Brain at first. Somewhat still am. Not all of it can stand its ground. That said, there are some high-level lessons in there worth nothing, as you can see from the 3 I outlined above. If you know your food, and think you can safely distinguish between what’s good and what’s not, go for it!

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Who would I recommend the Grain Brain summary to?

The 14 year old, overweight teenager, who is determined to do something about it, the 57 year old never-quitter, who runs on only 6 hours of sleep most days, and anyone who doesn’t believe there’s just one right diet out there for them.

Last Updated on August 1, 2022

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Niklas Göke

Niklas Göke is an author and writer whose work has attracted tens of millions of readers to date. He is also the founder and CEO of Four Minute Books, a collection of over 1,000 free book summaries teaching readers 3 valuable lessons in just 4 minutes each. Born and raised in Germany, Nik also holds a Bachelor’s Degree in Business Administration & Engineering from KIT Karlsruhe and a Master’s Degree in Management & Technology from the Technical University of Munich. He lives in Munich and enjoys a great slice of salami pizza almost as much as reading — or writing — the next book — or book summary, of course!