What Happens To Your Body
Though the research is not conclusive, a 2016 study published in the Journal of Nutrition and Metabolism found that fasting before morning exercise actually increases fat oxidation, potentially encouraging the potential for weight loss during exercise. During physical activity, your body uses carbohydrates as fuel if you’ve been fasting for a while, your body naturally turns to other energy sources when carbs aren’t available.
As registered dietitian Chelsea Amengual of Virtual Health Partners told Healthline, ” your stored carbohydrates â known as glycogen â are most likely depleted, so you’ll be burning more fat to fuel your workout.”
So, basically, the fasting body first depletes sugar-heavy glycogen stores. When those stores are depleted the body moves on to burning fat for energy. Over time, your body “learns” to rely on that process, encouraging itself to burn fat more efficiently. Four studies assessed by the journal Cureus in 2018 indicated that intermittent fasting is an efficient weight-loss method, regardless of body mass index.
Read more:How Intermittent Fasting Can Get You Lean
Understand The Side Effects
Bad Sleep Quality
While some people snooze like babies when fasting, others will experience poor sleep quality, having difficulty getting to sleep at all.
This can come from many aspects of the fasting experience :
- When you fast, theres a natural increase of noradrenaline and cortisol, it mostly comes from the stress fasting puts on your body. That could keep you awake unexpectedly
- Eating is a huge part of the circadian rhythm, your internal body clock. Removing food from your daily habits will alter it and can mess it up at first. Meaning going to sleep will be harder, you might wake up during the night or suffer small insomnias
- Some foods, especially carbs, can help promote sleep by producing tryptophan, which converts into serotonin, a precursor to melatonin. Melatonin is the sleep-promoting hormone
This side effect shouldnt impact your whole fast though, you might experience it a day or two, but your body will eventually catch up.
What I would advise you to do, if you feel like getting to sleep is really hard, is to only go to bed when you feel tired.
Thisll lead to less hours of sleep, but at least when you go to bed, you should be able to fall asleep quickly.
Dizziness, Nausea, Fatigue, Headaches, etc.
Often some of these side effects will come during the fast, generally on days 2, 3, or 4.
Here are a few reasons you might experience these :
The best way to fight these symptoms is to :
Poor Training Experience
Hunger and Cravings
Let me tell you: this feels great!
What Not Exercising While Fasting Does To Your Fitness
Indeed, one of the reasons most people lose muscle when reducing calories and losing weight is that they fail to lift weights. Another big reason is they fail to eat enough protein, of course, but simply by lifting weights during calorie deficits, we can retain muscle mass. Since a fast is by definition an extreme reduction in calories, exercise becomes all the more important.
Okay, so exercising during a fast is a Good Move. How should you exercise?
The short story is that for short fasts , you should exercise the way you normally do.
For extended fasts, from 48 hours to a week or more, you should still exercise, but a little differently than normal.
Lets get into it:
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Benefits Of Combining Intermittent Fasting And Workouts
Here are some of the amazing benefits of working out in a fasted state.
Benefits Of Fasting For Metabolic Health And Beyond
IF practices have demonstrated short-term positive impacts on patients metabolic health, with a recent systematic review reporting significant reductions in weight and waist circumference in overweight/obese patients. These findings were reproduced in both calorie restricted and eucaloric regimes, indicating a physiological benefit independent of reduced caloric intake. Thirty days of eucaloric IF in healthy volunteers has been associated with improved proteomic signatures and the upregulation of proteins involved in immune system regulation and DNA repair . It is hypothesised that this effect may improve individuals health by reducing the risk of developing long-term conditions related to chronic inflammation.
The interplay between IF and metabolic regulation may involve the circadian system. Recent studies on circadian rhythms have shown a diurnal variation of insulin and blood glucose levels. This raises the possibility of a time-of-day variation in the metabolic response to calorie consumption which is independent of the amount eaten. This hypothesis is supported by the finding of an increase in adiponectin following TRE in physically active participants. This finding may also provide a practical example of the aforementioned circadian rhythm hypothesis.
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Ketosis For Fat Loss#
Perhaps the number one reason most people turn to fasting is to burn fat andlose weight. When the body is consistently being fed by sugars, it uses thissugar for energy. Deprive the body of carbs, and it will have to look somewhereelse for fuel.
When the body switches from sugar to fat burning, this is called ketosis.Burning fat for fuel stabilizes blood sugar and reduces insulin resistance,2,3 and can even improve exercise performance.4
Ketosis is fastings most sought-after benefit. But for most people, it wontoccur until at least 22 hours into your fast. So, break your fast at 24 hoursand youve only spent a short time in ketosis. To maximize this benefit andcontinue to burn fat, youll want to fast for longer.
Fasting And Exercise Are Becoming More Popular Among Endurance Athletes
Zach Bitter is an ultra-endurance athlete who has competed in over 40 ultramarathon competitions. He also set an American record of running 100 miles in 11 hours, 40 minutes, and 55 seconds.
During a recent interview with me he talked about using body fat for fuel:
What Ill do is I try to eat as little as possible without sacrificing performance. The reason for that is because I see eating as an extra variable. Its another task Im giving my body. If I can get away without eating something, then I want to do that because its going to require less blood diverted to my stomach for digestion, which is another reason why I really dont eat a whole lot of fat while Im doing these events, either.
Even at your leanest state, the leanest athletes have enough body fat to get them through a long event like that, especially when you put into consideration whatever glycogen stores they had and anything theyre eating along the way. Theyve got plenty of body fat. The fuel tank is much larger than your glycogen reserves.
Watch his amazing interview here:
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Training In The Fasted State
Studies are starting to demonstrate the benefits of such training. For example, one study looked at muscle fibres both before and after training in the fasted state. This means that you fast for a certain period of time, usually around 24 hours, and then do your endurance or other training. The combination of low insulin and high adrenalin levels created by the fasted state stimulates adipose tissue lipolysis and peripheral fat oxidation .
Other studies had already shown that the breakdown of intramyocellular lipids is increased by training in the fasted state. Six weeks of training in the fasted state also induced a greater increase of fatty acid binding protein and uncoupling-protein-3 content in muscle.
What does this mean in plain English? It means that our bodies have the ability to adapt to whats available. When we fast, we deplete much of the stored sugar . Our muscles then become much more efficient at using fat for energy. This happens because muscle learns how to use the fat as energy by increasing the amount of proteins that metabolize that fat. In other words, our muscles learn to burn fat, not sugar.
Looking at muscle cells before and after exercise in the fasted state, you can see that there are more muscle bundles, but also that there is a deeper shade of red, indicating more available fat for energy.
Epoc: How To Oxidize Fat While Not Exercising
Intermittent fasting has been shown to enhance fat oxidation when combined with both endurance and resistance training. Although not directly related to intermittent fasting, it is worthwhile to briefly discuss the differential effects of various exercise programs on fat oxidation, independent of fasting.
The U.S. Department of Health and Human Services and the American Heart Association both advocate for 150-300 minutes of moderate or 75-150 minutes of vigorous physical activity each week, or a combination of the two.38 Running is one of the most popular types of exercise.39 It is associated with multiple health benefits and an excess longevity of three years compared to non-runners. Running commonly is the first type of exercise done for weight loss.40
Excess post-exercise oxygen consumption is the condition in which a prolonged period of increased caloric expenditure occurs after exercise is completed, typically supported by fat oxidation.41 Typically, this is intensity- and duration-driven. Compared to steady state running, several alterations in exercise programs can cause EPOC, many of which are timesaving as well.
An even more efficient way to induce EPOC is high-intensity interval training . HIIT consists of a warm-up period, and then alternating periods of hard and easy exercise .
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My Experience With Trying Omad
During my time experimenting with OMAD, I ate once a day multiple times, but never for an extended period of time. My longest streak was five days. Several times, I lifted weights, played full-court basketball, or did other types of strenuous exercise in a fasted state.
Here are my three most important takeaways from trying the OMAD diet:
How The Benefits Work
Broadly speaking, the benefits of fasted exercise fall into three categories: metabolic benefits, hormonal benefits, and fitness benefits.
When you fast, your body shifts from a predominantly anabolic state to a catabolic state .
And while neither anabolism nor catabolism is inherently good or bad, our bodies do best with a balance of both. Therefore, intermittent fasting offers advantages over eating three meals per day, every day.
Essentially, the metabolic benefits of fasting translate into long-term health benefits due to effects like increased use of fat as a fuel and supporting autophagy .
And similarly, when you exercise, your body must use available energy to meet the metabolic costs of physical activity.
If you exercise in a fed state, your body can use calories from the food you just ate.
But if you exercise while fasted, the exercise increases the demand for stored energy, thus further enhancing the metabolic benefits of your fasting periods .
And the ability to burn fat is important for everyone, not just people who want to lose weight.
For example, the synergy between fasting and exercise supports better insulin sensitivity and enhances your bodys ability to switch between carbs and fats as fuel sources, which may support overall health .
Additionally, favorable hormonal changes occur, such as higher HGH levels and decreases in hunger hormones .
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Benefits Of Fasting Aerobic
Improving Insulin Sensitivity and Insulin Resistance
Insulin sensitivity: In recent years, a large number of domestic and international studies have shown that fasting aerobic exercise can improve insulin sensitivity, but glucose and insulin metabolism under fasting exercise is a very complex and interesting thing. In the fasting state, the bodys glycogen is consumed overnight and blood glucose is at a low level, when glucagon, which promotes catabolism, is high and insulin is low. It can promote glycogenolysis and gluconeogenesis, significantly increase blood glucose in addition, it can also activate lipase, promote the notice of lipolysis to strengthen fatty acid oxidation, so that ketone bodies increase.
Improvement of diabetes and metabolic diseases
Type 2 diabetes is a chronic metabolic non-communicable disease characterized by chronic hyperglycemia and insulin resistance caused by various factors such as genes, environment and lifestyle . Although insulin resistance and -cell failure are considered to be the main causes of the development of type 2 diabetes, a large body of evidence suggests that diabetes is a systemic inflammatory metabolic disease. At present, diabetes is still incurable, so it is also known as chronic cancer.
Aerobic capacity
Weight loss
Autonomic function
Other benefits
Intermittent Fasting May Make You Feel Sick
Depending on the length of the fasting period, people may experience headaches, lethargy, crankiness, and constipation. To decrease some of these unwanted side effects, you may want to switch from adf fasting to periodic fasting or a time restricted eating plan that allows you to eat everyday within a certain time period.
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Cardio And Intermittent Fasting
The hormonal benefits you get from exercising in a fasted state are related to the depleted muscle and liver glycogen stores that occur when you fast. Doing cardio while intermittent fasting is fine, but your performance will hinge on how fat-adapted your body is . If youre new to fasting and exercise, you can expect your performance to drop a little it can take up to six months for some athletes to fully adapt their endurance to this new fuel source. For example, if youre a competing athlete, and your race performance is your primary goal, dont switch to fasted training a couple of weeks before a competition.
If you are doing cardio in a fasted state, avoid extending the fast post-workout, and opt to refuel after you finish.
What To Eat And When
Its understandable if a person is skeptical about not eating before exercise. But heres another perspective to consider: eating before a workout, or simply divulging in protein shakes can spike your sugar and insulin. Its similar to eating lunch and going back to work. How many people have felt sluggish and sleepy after eating lunch? The results can be jarringno hormonal response, no stamina for your workout, and no energy.
Its also important to look at it from a long-term perspective: we are told to consume a lot of carbs such as energy gels, protein shakes and other energy boosting foods to maintain our energy levels. Unfortunately, athletes who consumed high amounts of carbohydrates increase the risk of developing autoimmune degenerative diseases, inflammatory conditions and other ailments when they hit their 50s and 60s.
Even though they stayed fit, they eventually realize that it wasnt healthy. You can burn all that sugar, but it can have a negative effect on your mitochondria. In other words, burning all that sugar can cause a ton of oxidative stress which causes a lot of injury to your DNA.
Another point is to use naturalelectrolytes, specifically whole sea salt. This, as opposed to a Gatorade sports drink, is pivotal in the post-workout phase. The cold body factor that comes with exercise, and most specifically in fasting, is often eliminated by salt.
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So What Happens During A Fast
Its just the food-storage process in reverse. First, your body burns the stored sugar, then it burns the stored fat. In essence, during feeding you store food energy. During fasting, you burn energy from your stored food .
Note that the amount of energy that is used by, and available to, your body stays the same. The basal metabolic rate stays the same. This is the basic energy used for vital organs, breathing, heart function etc. Eating does not increase basal metabolism except for the small amount used to digest food itself .
If you exercise while fasting, the body will start by burning sugar. Glycogen is a molecule composed of many sugars all put together. When it comes time to use it for energy, the liver simply starts breaking all the chains to release the individual sugar molecules that can now be used for energy.
How To Reduce Intermittent Fasting Side Effects
Easing into an intermittent fasting plan can help your body adjust, according to McManus. “Slowly reduce the time window for eating, over a period of several months,” she advises.
You should also:
- Continue your medication regimen as recommended by your doctor
- Stay hydrated with calorie-free beverages, such as water and black coffee
- Choose a modified fasting plan approved by your doctor if you need to take medication with food.
Image: erdikocak/Getty Images
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Eat The Right Meals After Your Workout To Build Or Maintain Muscle
Dr. Niket Sonpal says the best solution for combining IF and exercise is to time your workouts during your eating periods so your nutrition levels are peaked.
And if you do heavy lifting, its important for your body to have protein after the workout to aid with regeneration, he adds.
Amengual says to follow up any strength training with carbohydrates and about 20 grams of protein within 30 minutes after your workout.
