Caloric Restriction vs. Fasting: The Science - Clovis

Caloric Restriction vs. Fasting: The Science


Something I hear all too often is the belief that fasting is dangerous, “bad for you” and confusing. With all the documented longevity and fat loss benefits one can get from a full fast, it’s disheartening (to say the least) to see people write it off so definitively.

I can understand why people get confused, especially if you find yourself in the beautiful vortex of the Clovis Academy. One week I’m preaching about how horrible chronic caloric restriction is for your fat loss goals and the next I’m telling you how great it is to stop eating altogether!

I can almost hear your brain scratching itself… Huh?

So today, I’m here to explain the difference between caloric restriction and full fasting. Beware, I’m going to get a bit geeky about it…

I want to start by dispelling the blatant and ridiculous lie that fasting is harmful to you or somehow “unhealthy.” I believe this assumption snuck up on as we gradually started losing trust in our own bodies... and started trusting big food companies. You know, the ones that tell us we need to eat and snack every few hours. God forbid the dreaded energy crash! We started believing we somehow “knew better” than mother nature and tried to prove her wrong. Let me tell you a little secret: you can’t outsmart mother nature, stop trying.

Fasting, as a religious practice, goes back thousands and thousands of years. There is not a religion out there that hasn’t incorporated some form of fasting into hyper-spiritual practices.

Fasting, as a way of life, is also how we survived for millions of years. Do you think our hunter-gatherer ancestors “stopped for a snack” in the middle of hunting mammoths? Do you think they grabbed a Larabar to “fuel up” before they started the day? Hell no!

They fasted. Each and every day. Naturally. Because they had to. Because they had to hunt everything they ate. And sometimes they went without food very long periods. And their bodies knew precisely how to handle it!

Okay, okay. I’ll get off my soapbox now. Time to get into the science of why caloric restriction is so much different than fasting.

Chronic Caloric Restriction:


I talk about the dangers of chronic caloric restriction all the time in the Clovis Academy, so if you want to nerd-out on it, even more, you can watch this AMA or read this blog post...

The primary reason why chronic caloric restriction is detrimental to your health and fat loss goals is hormones. Our hormones run the entire show, and when we put our bodies in long-term starvation mode, everything gets messed up.  

A traditional “caloric restriction diet” (the kind you’ll get from about every corporate-gym-personal-trainer-fitness-junkie) looks a bit like this: 800-1,200 calories a day, spread out into 5 small meals consisting of lean protein (like dry chicken breasts) and carbohydrates (like 1 cup of brown rice). Sound familiar? And notice something important here: this diet includes ZERO FAT (a macronutrient human beings can’t live without).

On a diet like this, you’ll lose some weight for the first month or so (as your body tries to figure out what the hell you’re doing) and then, without fail, you’ll plateau. You’ll stop losing weight or, even worse, start gaining it back. Here’s why:

As you continue to keep your body in a state of extreme caloric deficit, your hormones adjust to their new reality. With sporadic feeding… with little to no fat consumption, your body freaks out, goes into survival mode and starts hanging onto every fat cell available.

Remember, we need fat to survive. We will literally die without it. And our bodies are brilliant. Therefore, when we experience long periods without receiving any fat and barely enough calories to function, we begin to hold onto energy stores and shut down specific bodily functions to preserve energy. All because the body is operating under the belief system that essential fat will not be delivered any time soon.

The body is genuinely confused here… because it’s still receiving food, so it’s not “actually” starving. So, the mechanisms of full-blown fasting don’t kick in at all. Let’s say your BMR was 1,800 calories per day, and you decide to start giving it just 800. The body will adjust to the new environment and, again, shut down certain organ functions to preserve energy! It will lower its own BMR down the 800 you’ve trained it to get used to. The new BMR is now firmly set at 800 and weight loss completely stalls. If you start eating over 800 calories per day, the weight you initially lost comes back because you’re now “technically” eating a caloric surplus! This is outlined wonderfully in “The Biggest Loser Study.”

Fasting vs. Caloric Restriction:

When you’re genuinely fasting (not to be confused with a caloric deficit), the body has built-in mechanisms to keep you healthy! For instance, it spikes noradrenaline which holds your BMR at its proper set point, say 1,800 calories. On top of that, during prolonged fasts, Growth Hormone can spike by as much as 300%, which preserves lean muscle tissue and ensures the weight loss you’re experiencing comes from body fat! If the body is still burning it's normal 1,800 calories per day, it has to get that energy from somewhere. Where does it get all that energy?! From your stored body fat. The Holy Grail of fat loss. This entire process is, quite literally, the reason the human body stores body fat to begin with. To help us survive in times of food scarcity! Mother nature is a straight-up genius!

Phew, that was important, so I really hope it made sense…

This, in a nutshell, is why chronic caloric restriction doesn’t work.

Now, let’s get into why fasting does work and is one of the most natural and most beneficial things you can do for your health and fat loss goals.

Insulin is the #1 driver of fat storage. Period. Insulin is a storage hormone, and it is the primary driver of obesity. If you have chronically elevated levels of insulin, odds are, you will become overweight and eventually obese. If you have chronically elevated insulin levels for too long, you will become Type 2 Diabetic.

Insulin levels drop when we are in a fasted state. Insulin levels rise when we are in a fed state. It’s about as simple as simple gets.

Here’s a quick visual...  

So what makes insulin levels rise? Food. Most notably, carbohydrates.

Carbohydrates have the most significant impact on blood glucose levels. Insulin is recruited to clear the glucose from the bloodstream and shove it into muscle or fat cells. The more glucose in the blood, the more insulin is released, the more glucose is stored. This is why you often hear people talk about the Glycemic Index. Foods with a high Glycemic Index impact blood sugar and thus insulin levels the most.

I gave you this short lesson to drive the point home that lowering blood sugar and insulin is the key to sustainable fat loss. You can achieve this by carefully selecting the foods that you eat. This is always a good idea. That’s why I started a Paleo nutrition company, to help people navigate their food choices and thrive on a diet filled with nutrient-dense, unprocessed, whole foods. But that brings me to my next point...

Even if you carefully select each and every food item that you consume, the results will not be nearly as robust as full-blown fasting. Fasting is the single most effective way to reduce insulin and blood glucose levels in the body rapidly. The results can sometimes be hard to believe!

I have been researching nutrition and fitness for over 15 years. I am a Certified Nutritional Therapist, a Specialist in Sports Nutrition, and a Specialist in Fitness Nutrition. I have helped over 600 clients transform their health, and I can safely say that throughout my entire career, my body of work, and experience, I have yet to find a single therapeutic modality more powerful than fasting. The results I have seen people achieve through this simple practice that has been available to us, for free, since the dawn of time is nothing short of amazing.

In short, the differences in caloric restriction and fasting are significant and essential to recognize. Long-term caloric restriction will send you into a spiral of hormonal imbalances and metabolic deficiencies. But don’t fret, because fasting can fix all that! Of course, I'm not saying fasting is right for everyone! But when used in the right way, in the right person, a fast can be one of the most beneficial tools for a long, healthy, vibrant life.

If you're interested in exploring all of the ins and outs of fasting, including intermittent fasting, prolonged fasting, and even bone broth fasting... Check out my e-book, The Perfect Fasting Protocol right here...