Many “diet plans” involve limiting calories, especially in the carb category. And while we tend to focus a lot on the effects of diet change on the body, one area that doesn’t get a lot of attention is the most important body part of all: your brain.
Your brain weighs about three pounds, give or take. For the average person, that’s about 2% of your body mass. Not a lot. What most people don’t realize, however, is that the brain is the most energy intensive organ in the body, using some 20% of your daily metabolic burn.
Your brain’s preferred food source is glucose—essentially carbs converted into sugar in the body. But while your brain may be a high-functioning organ, it has a very low storage capacity. It can’t keep much glucose on hand. So it prefers that the “rest” of your body keep a decent supply of glucose to meet its high demands.
Now, not only does your brain need more energy on average than any other individual organ, it’s also at the top of the command chain—and that mens that what the brain wants, it tends to get.
Let’s distinguish that for a moment from what you want. You, the sparkling, lovely individual, may want to lose weight. Your brain, however, the grey matter built from millions of years of evolution, wants energy to survive and thrive.
So what happens when you embark on, say, a low-carb diet to lose weight? A couple of possibilities come to mind:
1. Your brain has less glucose to run on, so it doesn’t work as well. As Holly Taylor, a psych professor at Tufts University puts it in this Forbes article:
“The brain needs glucose for energy and diets low in carbohydrates can be detrimental to learning, memory, and thinking.”
If you can’t learn and think as well when you begin to change your diet, what are the odds you’re going to be on your mental game to continue that diet? Add to that the possibility that exerting willpower, a necessary ingredient for lifestyle change, uses up blood sugar, and you make the problem worse.
Result: You lose your mental game and the ability to stick with your plan. Plus you get hangry.
2. Your brain steals the glucose from other places. The brain is going to fight to keep its supply of sugar energy, and since it’s in charge, it’s going to get what it wants. If that extra energy comes from the rest of your body, how much does that impact your ability to be more active, another critical part of weight loss? And what does it do to your appetite?
Result: You lose energy, or become ravenously hungry. Or both.
Either of those scenarios might make it hard to change your diet. Both of them together can send your wagon crashing faster than you can say blood glucose level.
Now, your brain can also run on ketones, which it gets from breaking down fatty acids in the liver. But it takes time for the brain to switch over, and in the meantime, you’re hangry, and at risk of just going back to whatever food source is convenient. And convenient has a way of meaning crap.
So what to do?
Based on our glucose-hungry brain, it makes sense to look at diet changes in the context of blood sugar–in particular, trying to avoid big fluctuations.
- Make diet changes moderately. Suddenly deciding to starve yourself is a good way to either fall into either or both traps above. Make changes steadily and gradually.
- Eat complex carbs. Don’t confuse low carb with NO carb, or simple carbs with complex ones. A chocolate bar has a lot of carbs. A salad has a lot of carbs. But they’re different kinds. When you think “low carb” think “low SIMPLE carb”. In short, don’t give up vegetables. They work wonderfully to create fuel for your brain.
- Eat healthy protein. Protein works wonders to keep the “hangries” at bay!