That is the question and a rather daunting one at that. Whether you are just getting into fitness or are a seasoned vet in the space, you have likely come across the idea of fasting and spent some time pondering this topic. Perhaps you have even fasted a time or two with mixed conclusions. I am neither for or against it for you because, well, I’m not you, but I do believe there is merit for it in some degree for most people. Let’s look at some benefits and close with some recommendations. But first, let’s define it.

Fasting Defined

Fasting for our purposes here means to forego eating for a period of time typically for physical, psychological, or spiritual reasons. This blog will focus mostly on the physical (or metabolic) side of fasting. Some of the purpose for it in today’s culture is as result of understanding cultures in the past. Physiologically, which just means the basic functions of the human body, aren’t radically different than that of our ancestors and as such, one could stand to reason that they were forced to spend time without food. Now, they weren’t intentionally not eating as the term fasting suggests. In fact, they were actively trying to eat, foraging and hunting food, as the lands they inhabited and the seasons provided. I don’t know about you, but I can without fail say that I don’t worry a lot about IF I am going to eat again. It’s a matter of when I am hungry. We could rabbit-hole on all of that too because what is actual hunger? Sometimes you may feel a hunger pang and you just need to relieve yourself. Other times, it’s simply the body putting in a request for minerals, electrolytes and clean water. The signals get confused and we assume sensations in the gut mean we need to eat. The bottom line is that our genes adapted to fasting and based on the rise in obesity, diabetes, other metabolic disorders, and all the chronic diseases that are a product of those, we have yet to adapt favorably to feasting.

The Benefits

Benefit One: Autophagy

No discussion on fasting would be complete without at least a briefing on autophagy. Autophagy is a fancy word used to describe your body’s internal trash removal service. If you eat food as I suspect you do, food goes into your body, it ideally gets broken down, it then nourishes your cells after entering the bloodstream, and once those jobs are finished, it’s time for the food to make its grand exit in the nearest latrine. As we produce this waste daily, our cells are producing and collecting waste on the small scale or at least they should be. When we constantly eat, these cells are working around the clock to utilize the food coming in. They, however, don’t pay much attention to the bags of trash that are piling up. They are too busy sorting through constant barrage of digestion by-products. Fasting puts a halt to all of this. Fasting causes these cells to shift their focus. They focus on the process called autophagy. When you stop eating, it gives these busy cells a break and when they don’t have production quotas to meet with incoming food, they stop, assess the mess, and then redirect their attention to clean up. To better illustrate this process, think of it this way: you cancel your trash pickup service. You take one, maybe two bags of trash out per week. The first week, it’s not a big deal. Just a couple bags of trash in the garage. Weeks though turn into months. Months turn into a year, a year turns into three, until finally one day amidst the heaping pile of garbage and flies, your wife cries out, “Can we please get our trash service back?!” This is what happens internally when we constantly feed and our cells never are given a break to attend to clean up. Get your trash service back.

Benefit Two: Reduction in Insulin and Blood Sugar

Our blood sugar / glucose level elevates when we eat. The body must decide what to do with the increase in circulating blood glucose because blood sugar uncontrolled is dangerous. The decision is to tell the pancreas to secrete insulin. Insulin enters the bloodstream and hops on various cells throughout the body and is like a bouncer (insulin) at a club (cell) where Glucose is the high profile name on the guest list. Insulin opens the door to the cell and begins hollering at all the glucose molecules to come on which lowers circulating blood glucose levels as they leave the blood stream and enter the cell. Chronically high blood sugar levels is in essence what diabetes boils down to. It’s an inability to clear the circulatory system of excess blood sugar either because the pancreas doesn’t make enough insulin or the receptors just aren’t sensitive insulin any longer. How do you fix that? Eating fewer carbohydrates or eliminating carbs of the processed and refined variety goes a long way, but you can expedite that by just not eating for a period of time. The type of food does impact just how high your blood sugar level goes and subsequently how much insulin is secreted by the pancreas, BUT your blood sugar level will rise slightly as a result of eating anything. Why would anyone care about lowering blood glucose levels? For many, many reasons but one really important one for optimal fitness and health is the ability to access body fat for fuel. Other ways exist (resistance training, physical activity, blood sugar stabilizing supplements, etc.) but if you want to access fat, blood sugar levels will have to drop enough to give the body a need to develop the machinery to use fat as fuel.

Benefit Three: Resetting Portions

This benefit is somewhat anecdotal, but in my personal experience with fasting and in that of individuals with whom I have had the opportunity to work with over the last decade and half is a feeling of fullness that happens sooner at the meal immediate post fast. Now that’s highly contextual because if you hit up a drive through window and crush a calorically dense, nutrient void meal, you most likely won’t feel full. Bloated maybe, but satisfied not as much. Most folks have reported back to me that eating a balanced, “healthy” meal after even shorter fasts has had them feeling fuller sooner and at times not even being able to finish off a meal that they normally would have no issue devouring. Fasting appears to assist in reestablishing portions that so often seem to progressively grow with time.

Recommendations for A Fast

Prior to fasting, I would encourage you to check with a doctor or medical professional to make sure that a fast is safe for you to do. If you take a plethora of medications or have severe diabetes, there could be some dangerous if not deadly consequences to going without food for extended periods of time. Pregnant and breastfeeding women should avoid fasting. Short fasts most likely would not be a problem for most, but I’m not there to assess your specific situation, so it would be wise to consult with someone who is.

What to Have While Fasting

If you are clear to fast, then you are ready to start not eating. But wait, “I can’t have anything while I fast?” I know that there are a lot of “does this break a fast” kinds questions out there so here is a list of things you can have while on your fast. It’s pretty simple.

1. Water with minerals added (lemon, lime, Celtic sea salt)

2. Black coffee

3. Herbal teas like matcha, black tea, chamomile, Yerba mate, etc

As a general rule, if it has calories, it breaks the fast.

Structures of Fasting

1. Intermittent Fasting (IF)-Whether you like it or not, you fast when you sleep unless you have some sort of IV nutrition mainlined into your bloodstream. IF is the most manageable fast and is the best place to start. Twelve to 16 hours is a solid duration to obtain some of the benefits from above without getting too deep into the hunger pangs. This could be as simple as finishing dinner at 8p and not eating again until 12pm essentially skipping breakfast for a quick and cool 16-hr fast.
2. Long Duration Fasts-These are normally reserved for those who are a bit more metabolically adapted to going without food and can access body fat as a fuel. This is not a good place to start! Fasting for 24 hours to 5 days in a row and everything in between would fit the criteria for a long fast. Five days has been reported to have a complete reset effect on the immune system. Dr. Daniel Pompa can tell you more about a 5-day fast in this video Preparing for a 5-Day Water Fast.
3. The Fasting Mimicking Diet (FMD)-Perhaps the idea of not eating anything for a while terrifies you. The FMD allows you to eat, but at much lower quantities for 5 days allowing you to attain the benefits of autophagy but without completely eliminating food. Valter Longo Ph.D. has a podcast episode with Dr. Mercola about this protocol.

Before starting a fasting regimen, do your homework. My blog may be starting place for you, but look for credible people, organizations and podcasts to expand your understanding of the topic. Many more benefits exist. A lot more details are out there about how to maximize the fast.

Generally speaking, food, or the appearance of food-like substances, is abundant in our western culture. We don’t have to concern ourselves with if we will get our next meal. We only worry about, sometimes obsessively, what and when.

In sum, fasting is a great way give the body’s operating system a chance to reboot and update the software. To our detriment, we are working later and eating later in the day. We are working earlier in the day and eating earlier in the day. Fasting gives us a chance to restore some balance and enhance your body’s ability to perform.