I’m a huge fan of fasted training. It feels right, it feels “Primal.” And it jibes with my sense of how life was back in the hunting and gathering days: if you wanted to eat, you had to go hunt, and you had to hunt on an empty stomach (because you didn’t have much food laying around, let alone a refrigerator full of it). This is the natural state of animal life in the wild—get hungry, perform physical tasks to obtain food, eat—and it always made intuitive sense that following that pattern when working out as a modern human would confer special benefits. Our big disconnect nowadays is that food is separate from physical labor. You no longer earn your meal on a visceral, physical level. There are social benefits to this new setup, but there are also metabolic, health, and fitness consequences.
Fasted training could be a way to correct that disconnect and restore the ancient relationship between food and movement. It’s plausible. But what does the research say?
Today we’re taking a peek under the hood and looking at some of the hormones involved in hunger and satiety, a.k.a. appetite hormones.
You might think of hunger as a gnawing feeling in your stomach and satiety as that feeling of fullness when you’ve eaten enough… or maybe too much. That’s how we experience the feelings we call hunger and satiety, true; but I’m talking today about the physiological drives to eat or stop eating that is driven by hormones.
Eating behavior is coordinated mostly in the brain by the hypothalamus, which acts as the control center for appetite. Hunger and satiety hormones deliver information from the body about how much energy you are taking in and whether you need more. The overarching goal here is energy homeostasis—balancing the energy coming in (via food) with the energy needed for the everyday functions of being alive.
When you have sufficient energy, your body is free to invest in growth, repair, and reproduction. Taking in more energy than you need can lead to excess fat storage and issues like hyperinsulinemia, insulin resistance, and metabolic syndrome. Energy deficits result in adaptations designed to conserve energy. In the long run, energy deficits might increase longevity, but they can also seriously undermine health and, for example, impair fertility.
Today I’m going to cover some of the key hormones that are involved in this delicate dance. This is by no means a complete list. Let me know in the comments if you have a burning desire to learn more about one of the hormones not covered here.
Fasting is a great tool for so many things. You can use it to regulate food intake and lose body fat. Fasting can help you shift body composition, normalize your appetite, and gain control over your relationship to food. Many people report cognitive enhancements from fasting, and it’s a surefire way to speed up the transition into ketosis and full-blown fat adaptation. There’s strong evidence that we look, feel, and perform best skipping the occasional meal—that it’s the evolutionary norm for humans not to have constant, unceasing access to food. After all, we didn’t always have 24 hour grocery stores and fast food restaurants. But what about fasting with a cold?
And what about intermittent fasting and the immune system? Should you fast at all when you’re sick? What about fasting with the flu? Or how about bacterial infections—can fasting help with those? These are actually some of the most common questions I receive. Because intermittent fasting seems to help with so many other conditions, it makes sense to wonder about its relationship to the immune response.
You’ve been keto for a few months now (or longer). You know what you’re doing. You feel good about where you are. You’re fat-adapted. You’ve got a slew of recipes under your belt, your gym performance has normalized, the keto-flu is a distant memory. And now, you’re looking to explore further. The natural next step is intermittent fasting.
But is it the right move?
Does intermittent fasting work if you’re keto?
The short answer is: Yes. Intermittent fasting works really, really well if you’re on a ketogenic diet.
Hi folks, today’s post comes from my friend Max Lugavere, New York Times best-selling author of Genius Foods and The Genius Life, which will be available for purchase on March 17, 2020. Max is a young guy, but he’s accomplished a lot so far, including an impressive bit of research and writing about longevity and how to age optimally with grace. I know you’ll enjoy Max diving into the weeds a bit about the nutrient sensors, proteins, and catalysts that may help us live long, healthy, thriving lives. This post comes from an excerpt from Max’s newest book The Genius Life.
From now until March 11, 2020 at 11:59 p.m. PST, enter for your chance to win a FREE copy of The Genius Life as well as Primal Kitchen salad dressings and Primal Sun. All you have to do is head over to Instagram, follow @marksdailyapple and @maxlugavere, and tag some friends in the comments of the giveaway post. Three winners will be selected and notified via DM. Good luck, and enjoy the excerpt.
When it comes to slowing down the clock, life extension is indeed possible. The catch? There are two: it involves calorie restriction, and it has only been successfully demonstrated in lab animals. Studying longevity in humans is a bit more challenging. We don’t sleep in labs, we live a lot longer, and we like to eat. (Correction: we love to eat.) So while most of us would happily opt for a 40 percent increase on our life spans like food-deprived lab rats seem to achieve, we need a better route to get there.1
Is intermittent fasting a good idea for people with thyroid issues?
It’s a common question. After all, we know that the thyroid gland is a sensitive barometer of overall caloric sufficiency in the body. If a fast sends a message of caloric insufficiency, and the body thinks “times are tough,” the thyroid may presumably down-regulate its function to slow down the metabolic rate and preserve energy and nutrients. Caution is justifiable.