It is no secret that many people abstain from eating in order to lose weight, or eat lighter to shed pounds. But, as most people know, not all weight loss regimes are equal.

It’s good to have a plan for how you will spend your time while fasting. Depending on your schedule, you may want to choose a type of exercise that you can do while fasting. Or, you may want to do more vigorous exercise while fasting. Fasting also helps you shed more fat during and after fasting.

Fasting and exercise go hand in hand. Both are used to combat various conditions, but why do we see people fast for different reasons? Some fast because of the health benefits it brings, while others do it to lose weight. So, which is better? It depends. For those who want to lose weight, there are two types of fasting. The first is intermittent fasting, where the body is allowed to consume only during a specific time period. This is usually done in a 24-hour window. During this window, the body is usually allowed to eat every few hours. The second type is also called fasting, but it doesn’t allow you to eat at all, but it is known as a “water fast”.. Read more about long-term fasting and exercise and let us know what you think.

Is it possible to exercise during Lent? It’s a common question, and the answer is straightforward: yes.

People believe that eating provides them vitality, therefore fasting and exercising at the same time will be tough. Some individuals who work in physically demanding professions believe they are unable to perform efficiently and effectively. What really is the truth?

Let’s consider what occurs when we eat from a logical standpoint. Insulin increases, signaling to your body that it should utilize part of the energy in the meal right away. The remainder is converted to sugar (glycogen in the liver). The liver generates fat when glycogen reserves are depleted (de novo lipogenesis). Food proteins are broken down into their individual amino acids. Some of it is utilized to restore protein, but the rest is converted to glucose. Dietary lipids are immediately absorbed into the gut. It is not digested further and is stored as fat.

Insulin’s primary function is to prevent lipolysis. This indicates that it inhibits fat burning. The glucose that is supplied with meals is distributed throughout the body and utilized for energy.

What occurs during the Lenten season?

Simply said, this is the opposite of food storage. Stored carbohydrates are burned first, followed by stored fats. You basically store energy from food when you consume it. When you fast, the stored energy in your body is burned (sugar and fat).


It’s important to note that the quantity of energy used and accessible to the body is unchanged. The basic metabolic process does not alter. This is the fundamental energy that powers the essential organs, breathing, heartbeat, and other bodily functions. Aside from the tiny quantity required to digest the meal, food intake has no impact on basal metabolic rate (thermal effect of food).

When you exercise while fasting, your body starts to burn sugar. Glycogen is a molecule made up of a number of different sugars. When it’s time to utilize it as an energy source, the liver simply breaks down all of the chains, releasing simple sugar molecules that may now be used as fuel.


Influence of glycogen on the wall

As previously stated, the short-term storage of dietary energy (glycogen) is comparable to that of a refrigerator. Nutritional energy may readily flow in and out, but there is a finite amount. Frozen storage is comparable to long-term storage (fat). Food is more difficult to come by, but you can keep a lot more of it. If you eat three meals a day, you’ll need to go to the supermarket three times a day and keep leftovers in the refrigerator. We put it in the freezer if there’s too much for the fridge.

What happens when you fast and work out? The body, on the other hand, receives its energy from the refrigerator. Because your body contains enough glycogen to last for more than 24 hours on a typical day, you must exercise for extended periods of time before you can tap into these reserves.


When glycogen reserves are low, endurance athletes may hit this wall. The picture of American racer Julie Moss crawling across the finish line of the 1982 Ironman triathlon, unable to stand, is probably the most dramatic example of running into a wall. Bonking is a word used by athletes to describe the full depletion of energy reserves in the short term. Some of you may believe that bonking relates to other four-legged activities, however this is a nutrition blog!

Changing to fat-burning mode

How are we going to get around this? During the IronMan race, your glycogen reserves will not be enough to keep you going. At the same time, you continue to store a lot of energy as fat. All of this energy is stored and unavailable during physical activity. The only reason it won’t work is because your body isn’t set up to burn fat.

You may teach your body to burn fat by eating an extremely low-carb or ketogenic diet. Exercising while sober may also teach your muscles to burn fat. Instead of depending on a finite quantity of easily accessible glucose throughout the race, you may now tap into your fat stores for practically limitless energy.

Sobriety education

The advantages of such learning are starting to be discovered via research. This research, for example, looked at muscle fibers in an empty condition before and after activity. This involves fasting for a certain period of time, typically about 24 hours, followed by endurance training or other activities. In a fasting state, the combination of low insulin and high adrenaline promotes adipose tissue lipolysis (fat breakdown) and peripheral fat oxidation (fat burning for energy).

In the starving condition, several studies have demonstrated that exercise promotes intramyocellular fat breakdown (IMCL – fat in the muscles). Fasting training for six weeks increased the levels of fatty acid binding protein and uncoupling protein 3 in the muscles.

In layman’s terms, what does this mean? This implies that our bodies have a remarkable capacity to adapt to any environment we find ourselves in. We eat the majority of our sugar supply while we fast (glycogen). Our muscles improve their ability to burn fat for energy. Because the quantity of protein that metabolizes fat increases, the muscles learn to utilize fat as an energy source. To put it another way, our muscles adapt to burn fat rather than sugar.


When comparing muscle cells before and after a fasting exercise, you’ll see that there are more muscle clusters, as well as a darker shade of red, suggesting that there is more fat accessible for energy.

What can high-performance athletes do with it?

Tim Noakes, a renowned physiologist and physician from Cape Town, South Africa, is a pioneer in recognizing the advantages of a low-carb diet for top athletes. Many national teams (such as the Australian cricket team) are now using these principles to annihilate their opponents. Low-carb, high-fat diets have helped NBA legends like LeBron James, Kobe Bryant, and Carmelo Anthony shed weight and extend their careers.

If this low-carbohydrate nonsense and starving training had a negative impact on their athletic performance, you can guarantee they wouldn’t be doing it. In fact, it’s the polar opposite. Steve Nash, an NBA player, does not consume simple carbohydrates. Do you drink Gatorade with added sugar? That isn’t going to help at all.


Another research looked at how 3.5 days of fasting affected different sports performances. Strength, anaerobic capability, and aerobic endurance were all assessed. During Lent, none of these markers decreased.

Sports that need a lot of endurance

The body simply shifts its metabolism from sugar to fat. However, for endurance athletes, the increase in accessible energy is a significant advantage since fat instead of sugar can store exponentially more energy. If you run ultramarathons, the capacity to utilize practically limitless fat energy rather than restricted carbohydrate energy implies you are less likely to crash and may even win the race.

You’ll probably notice a decrease in productivity while you adapt to these adjustments. It takes approximately two weeks to complete this task. When you deprive your body of sugar, it takes time for your muscles to adjust to utilizing fat as an energy source. They will lose energy, muscular strength, and general performance, but they will recover. As a result, although LCHF, ketogenic, and fasting diets may be beneficial for training muscle to burn fat, they require time to adjust.

Consider the following comparison. Consider our bodies to be a gasoline tank. We drive these massive tankers, but we only have so much fuel in the tank. We were stranded on the side of the road when we ran out of petrol, begging for assistance. But hold on, you say. It’s amusing. You have a full tank of gas in your car, but it runs out. What do you mean by that? This gas isn’t available right now.


Similarly, we store a significant amount of energy in the form of fat. Our muscles, on the other hand, have been taught to function on sugar and are low on energy, so we must continuously refuel, even if we have a huge reserve of fuel stored in the form of fat.

So, what is my greatest workout and fasting advice? Don’t be concerned. Carry on with your regular routine throughout Lent. You may exercise during Lent if you normally do so, or even if you don’t. You may workout whether you’re fasting for 24 hours or 24 days. Your muscles, on the other hand, may take up to two weeks to adapt to the fat. You may need to rest during the first two weeks of fasting, but you will rapidly recover after that.

Jason Fung, Ph.D.

At this point, I’m not going to pretend that I have unique insights into the effects of fasting and exercise. After all, I don’t have a PhD in nutrition and I’m far from being an expert on exercise physiology. However, for better or for worse, I think the discussion is important enough that I want to share some of my thoughts on it.. Read more about fasted weight training benefits and let us know what you think.

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