What if I told you that making one or two small tweaks to how you fast could completely change your results and make the entire process more effective? The difference between fasting now versus just five or six years ago is staggering. Thanks to cutting-edge science and a lot of real-world trial and error, our entire approach has been revolutionized. Sometimes, you have to leave your ego at the door and embrace change to make something better.
In this article, we’re going to dive deep into the major shifts in our understanding of fasting. You’ll learn what we used to believe, why it was flawed, and what the new, practical strategies mean for you. Get ready to apply these powerful changes to your own health journey, starting today. (Based on the insights of Thomas Delauer)
Key Takeaways
- Fasting as a Shock, Not a Routine: Instead of daily 16:8 fasts that can slow your metabolism, the modern approach uses occasional, more aggressive fasts as a beneficial shock to the system.
- Use Modern Tools: Don’t try to live like an ancestor. We have tools (like small amounts of carbs) to strategically manage stress hormones like cortisol and control our fasting experience.
- Focus on the Signal: Fasting isn’t just about restricting calories. It’s a powerful signal that triggers profound cellular and metabolic adaptations that improve your health long after the fast is over.
- The Repair Happens When You Eat: The fast initiates the breakdown process, but the real repair and rebuilding happen when you refuel. The quality of your food during your eating window is paramount.
- Refresh, Don’t Crush, Insulin: The goal is not to eliminate insulin forever but to use fasting to refresh your body’s sensitivity to it, creating a more harmonious relationship with this vital hormone.
- Aim for Metabolic Flexibility: The ultimate goal is to train your body to efficiently switch between burning fat for fuel and using carbohydrates when needed, making you more resilient and adaptable.
1. From Predictable Routine to a Strategic Shock
Not long ago, the world of intermittent fasting was all about predictability and convenience. The dominant strategy was the 16:8 method: fast for 16 hours, eat within an 8-hour window, and repeat it every single day. The logic was simple—it was an easy way to skip breakfast and consistently restrict your daily calories. While this can work for some, we started to see a problem.
When you do the exact same thing every day, your body, in its infinite wisdom, adapts. It gets used to the daily calorie deficit and starts to conserve energy. The result? Your metabolism can slowly downshift, and your metabolic rate may decline. You might also disrupt your natural cortisol rhythm, which is typically highest in the morning to get you going. By constantly skipping that morning meal, you’re fighting against your body’s innate hormonal clock. Now, we see fasting differently. Instead of a monotonous daily grind, we view it as a strategic shock to the system. You maintain a healthy baseline—say, three nutritious square meals a day—and then, a couple of times a week, you rip the carpet out from under your body with a longer, more aggressive fast. This forces your body into a short-term, controlled stress state where it has no choice but to adapt, creating changes that make you healthier and more metabolically flexible.
2. From an Ancestral Fantasy to Using Modern Tools
We used to look at fasting through a romantic, ancestral lens. We’d say, “What did our ancestors do? They fasted, and then they feasted!” This is a great concept if you’re actually living like our ancestors—outdoors, exposed to the elements, and physically active all day. But let’s be honest, almost no one lives that way anymore. We have climate-controlled homes, cars, and food at our beck and call.
Pretending we’re cavemen is fun, but it ignores the incredible scientific tools we now have at our disposal. Here’s a perfect example: when you’re deep into a fast, your body produces more of the stress hormone cortisol. In the past, you just had to tough it out. Now, we know how to manage it. You can have a single tablespoon of honey or a small portion of potatoes. This tiny amount of carbohydrates is just enough to blunt the cortisol spike, turn off that stress signal, and actually help you continue to burn fat more effectively. You are in control. You can use fasting as a tool, and you can use food as a tool to break it strategically. Embrace the advantages of modern life instead of being a slave to an idealized past.
3. From Calorie Restriction to a Powerful Signal
The old way of thinking viewed fasting almost exclusively as a method for fat loss and cellular repair (autophagy), focusing only on the act of taking away food. The benefit was seen as a simple equation: fewer calories in equals weight loss. While it’s true that you will restrict calories and that this has benefits, this view is incredibly limited.
Today, we understand fasting as a profound biological signal. It’s not just about the absence of food; it’s about what that absence triggers inside your body. The fast is a catalyst for a cascade of positive cellular and metabolic adaptations that continue long after you’ve taken your first bite of food. We’re talking about the upregulation of your body’s own antioxidant systems, the downregulation of inflammatory markers, and the powerful modulation of hormones. When you treat fasting as a random, powerful stimulus rather than just a diet, you free yourself from the obsession with counting calories. This mental shift is liberating and helps you avoid the disordered thinking that can come with fixating on numbers.
4. From Skipping Breakfast to Fine-Tuning Your Nervous System
For many, fasting was just a simple hack to cut out one-third of their daily calories by skipping breakfast. Again, this isn’t technically wrong, but it misses the bigger, more important picture. The modern focus has shifted to fine-tuning your body’s delicate systems, particularly your circadian rhythms and your autonomic nervous system.
When you focus only on calorie restriction, it’s easy to take it too far. People often continue to restrict calories even during their eating window, leading to a state of chronic stress. This puts your body into a constant “fight-or-flight” mode, dominated by the sympathetic nervous system. Is it any wonder people can’t stick to diets long-term? They’re constantly stressed and depleted. The new approach is much simpler and more sustainable: Eat healthy, nutritious food to nourish your body. Move your body. And then, occasionally, don’t eat. By doing this, you support your “rest-and-digest” parasympathetic state during your eating periods and use fasting as a targeted tool, not a chronic stressor.
5. From Focusing on the Fast to Prioritizing the Repair
There was an obsession with the fasting period itself. We thought the fast was when all the magic happened—when autophagy cleaned up old cells and stem cells were generated. We focused all our energy on what to do during the fast. In reality, the fasting part just starts the signal. The real growth and repair happen afterward, during your eating and sleeping periods.
Think about it like working out. You don’t build muscle in the gym; you break it down. You build muscle when you go home, eat adequate protein, and get a good night’s sleep. Fasting works the same way. The fast is the stimulus that breaks down old and damaged cellular components. But if you never provide the building blocks to rebuild, you’re just left in a state of breakdown. This is why the new focus is so heavily on what you eat during your eating window. You must provide your body with adequate calories, high-quality nutrition, essential minerals, and micronutrients to perform the repair work. I used to obsess over the fast itself, but now I realize it’s far more important to ensure my body is perfectly nourished so it can handle the temporary, beneficial stress of a fast.
6. From Crushing Insulin to Refreshing Its Signal
The old mantra was “low insulin, all the time.” The goal was to crush this hormone, to manually push it down and keep it there, believing it was the primary enemy of fat loss. While chronically high insulin is indeed a problem, trying to eliminate it entirely is misguided. Insulin is a vital hormone.
The new, more nuanced perspective is to use fasting to refresh insulin signaling. Think of it like rebooting a computer. By fasting, you give your cells a break from the constant presence of insulin. This makes them much more sensitive to its signal when it returns. The goal is to teach your body how to work in harmony with insulin, not to wage war against it. This allows you to become more metabolically healthy, so your body can handle carbohydrates appropriately when you do eat them. I don’t eat carbs for fuel; I use them as a signal. A small amount of carbs after a fast tells my body, “You are safe. You have fuel. You can turn off the cortisol and switch into repair mode.”
7. From Just Burning Fat to Building Metabolic Flexibility
Initially, the main draw of fasting was its ability to turn you into a fat-burning machine. By depriving your body of glucose, you train your mitochondria to become efficient at using fat for fuel. This is 100% true and a major benefit. However, the ultimate goal is something even more powerful: metabolic flexibility.
Metabolic flexibility is the ability to efficiently switch between fuel sources. You want your body to burn fat when you’re fasting or at rest, but you also want it to be able to use carbohydrates effectively when you eat them or during intense exercise. If you fast too much or restrict carbs too aggressively, you can lose your ability to tolerate glucose well. The real magic of a smart fasting protocol is that it trains your body to use the right fuel at the right time. My current strategy reflects this: I do a simple 12-hour fast every day (e.g., 7 p.m. to 7 a.m.). Then, two days a week, I do a longer 20-hour fast to get that metabolic shock. This approach builds a resilient metabolism that can handle whatever you throw at it.
Conclusion
Our understanding of fasting has matured significantly. We’ve moved away from rigid, daily protocols and toward a more flexible, strategic, and science-informed approach. It’s no longer about constant restriction or mimicking our ancestors. It’s about using fasting as a powerful, intermittent signal to enhance your body’s own systems, manage stress, and build true metabolic flexibility. By embracing these new principles, you can unlock the profound benefits of fasting in a way that is more effective, sustainable, and liberating than ever before.
Source: Thomas Delauer