In this excerpt from his new book Neurofitness, Dr. Jandial—a college dropout turned neurosurgeon—explains why intermittent fasting is so good for the brain.
Perhaps there is a reason why most of the world’s major religions call for periodic fasting. Intermittent hunger clears the mind, awakens the senses, and improves brain functioning. Plus it lowers your blood sugar, reduces your insulin levels, and helps you lose weight by reducing total calories. What’s not to love?
Well, the hunger. But it only lasts for a short time!
Consider our prehistoric ancestors, the hunters and gatherers who survived through feast and famine, abundance and scarcity. The real “Paleo diet” didn’t consist of just large hunks of meat. Many were the days and weeks they failed to catch an auroch or boar and went to sleep hungry.
But with the hunger pangs come benefits. Going without food for even a day increases your brain’s natural growth factors, which support the survival and growth of neurons. Evolution designed our bodies and brains to perform at their peak as hybrid vehicles. Metabolic switching between glucose and ketones is when cognition is best and degenerative diseases are kept at bay. As a recent paper in Nature Reviews Neuroscience put it: “Metabolic switching impacts multiple signaling pathways that promote neuroplasticity and resistance of the brain to injury and disease.”
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So how do you do it? Not by overloading on glucose or ketones [the energy source produced when the liver burns fat], but by altering the cadence of eating and letting the body do what it was designed to do during times of food scarcity.
I’m not talking about caloric restriction, which extends longevity in animals and may well do the same in humans. People who follow a serious caloric restriction diet, eating as little as a thousand calories per day, are always hungry. I’m talking about being intermittently hungry by forcing your body to burn its fat reserves once or twice a week. The exhaust from this, ketones, will not only keep your brain going during those periods of fasting and hunger but will actually improve cognition, grow the connections between neurons, and stave off neurodegeneration.
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I follow (or at least try to) an intermittent fasting diet, and I recommend it for anyone who wants to improve their mood and hit peak cognition. Here is my plan:
Fast twice a week
The goal is to hit two stretches of sixteen-hour periods without food. So choose two days, not back to back, and skip breakfast and lunch or lunch and dinner. When you add in the hours you sleep, it’s relatively easy to get to sixteen hours. Every Monday and Thursday, I skip breakfast and lunch and only eat dinner. Whatever my wife and sons are having, that’s what I have.
I’m not talking about just on fasting days; I’m talking about avoiding breakfast almost every day! Some people insist that breakfast is the most important meal of the day, but there’s no good evidence for that. The only time I eat breakfast is occasionally on the weekends, with my boys, just to hang out and be in the moment with them.
Salad for lunch
I rarely eat a sandwich or burger or anything with carbs. My routine is to have a salad for lunch. It’s a little painful.
No late-night snacks
This one is hard for me, especially after a long day or when I have fasted. But I try.
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Please keep in mind, I’m no extremist. I do go out to eat with family and friends, often. Sometimes I’m invited to a breakfast meeting and go with the flow. But I have made intermittent fasting part of my routine.
On days when I am operating, in fact, I eat nothing until late afternoon. I don’t even have a cup of coffee, because once I enter the OR, there is no skipping out to the bathroom. I am routinely in there working for eight hours straight without a break. It may sound surprising that I’m not dragging from lack of food, but quite the opposite: I find it keeps me more alert.
Excerpted from Neurofitness: A Brain Surgeon’s Secrets to Boost Performance and Unleash Creativity © 2019 by Rahul Jandial, MD, PhD. Reproduced by permission of Houghton Mifflin Harcourt. All rights reserved.
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