Scientific studies and the Nobel Prize in Medicine have transformed fasting from a mere fad to a popular diet (Levine et al. 20171).
Against this backdrop, information about the potential benefits and drawbacks of intermittent fasting has exploded. But which claims about intermittent fasting are myths, and which are facts?
Facts and Myths About Intermittent Fasting: Is It Scientifically Proven?
Intermittent fasting is more of an eating pattern than a diet. It involves eating within a specific period and fasting the rest of the day.
Although there are several forms of intermittent fasting, the most popular is fasting for a 16-hour window.
Therefore, when 16/8 intermittent fasting, you may only eat during a window of 8 hours per day, for example, from 12:00 to 20:00.
Ironically, many people have been practicing this method of fasting unconsciously for years. After all, all you have to do is skip breakfast.
Nevertheless, some skeptics believe that this way of eating could be wholly ineffective and dangerous for health.
And that’s mainly due to numerous fasting myths that have either been inadequately researched or put out there for marketing purposes.
Based on actual science, you will learn which claims about intermittent fasting are pure myths and which ones are true.
Top 10 Intermittent Fasting Myths Debunked by Science
Many people have a panic fear of fasting, even though it is a thoroughly natural state.
Yes, there were times in human history when there were no refrigerators nor grocery stores open in winter.
As a logical consequence, humanity has always had to fast for many days. However, numerous fasting myths have developed in the age of abundance that is difficult to get out of our heads.
Thus, here are the top 10 myths about intermittent fasting debunked by science:
Myth #1: Eating Small Meals Frequently Helps You Lose Weight
Which is the better consumer: the one who eats 1-2 times a day and thus has time to prepare a high-quality meal or the one who eats every few hours and therefore relies on convenience foods?
Unfortunately, it’s the latter.
With this in mind, advertising has educated us with adverse diet advice, including:
- Never skip a meal
- Snacks help you lose weight
- Many small meals boost metabolism
- You must eat six times a day to lose weight
This dietary advice gave rise to the notion that eating multiple meals increases the metabolic rate, causing the body to burn more calories overall.
Nonetheless, eating more often to lose weight is just as controversial as it sounds.
While a thermic effect of food does exist, requiring extra energy, mainly when proteins are digested, it cannot equalize the negative impact of snacking.
Accordingly, studies debunked this intermittent fasting myth since people who eat snacks eat more throughout the day (Stubbs et al. 20012).
Moreover, it is scientifically proven that snacks cannot help people lose weight (Cameron et al. 20103).
The reason for this is the influence of nutrition on our hormone balance. Ultimately, these messengers determine whether we gain or lose weight.
The primary storage hormone insulin is responsible for signaling cells to take glucose from the bloodstream and store excess energy as fat.
Therefore, the body produces insulin when food intake raises blood glucose levels.
Accordingly, researchers can already predict 75% of weight gain and loss in obese people using insulin levels (Kong et al. 20134).
Moreover, insulin prevents the breakdown of body fat (Meijssen et al. 20015).
Consequently, several meals inhibit insulin levels to drop throughout the day. Thus, you prevent not only fat loss but also promote fat gain.
Myth #2: Fasting Puts Your Body in Starvation Mode
That intermittent fasting causes the mysterious starvation mode is one of the oldest myths. The term refers to the fear that the body shuts down the metabolism to save energy.
However, against the backdrop of starvation mode, we have to distinguish between true fasting and conventional caloric restriction.
Intermittent fasting is not a conventional diet. Instead, it is an eating pattern that distinguishes between strict periods of feating and fasting.
It does not involve snacking and starving around the clock.
What people fear as the starvation mode is nothing other than the yo-yo effect of conventional diets.
And what is the lowest common denominator of conventional diets? Calorie counting!
How conventional calorie reduction can permanently restrict the basal metabolic rate is best shown by a study conducted on participants of the weight-loss TV show The Biggest Loser.
It showed that the participants who lost the most weight through calorie restriction still suffered from a significantly reduced basal metabolic rate six years later (Fothergill et al. 20166).
Eating in many small meals ensures that insulin levels barely drop throughout the day. Therefore, the body cannot break down stored fat for energy (Meijssen et al. 20017).
However, unlike fasting, the body can access lean mass due to the lack of growth hormone protecting muscle (Ho et al. 19888).
Consequently, daily caloric restriction decreases the basal metabolic rate. Ultimately, it must manage the restricted energy intake.
The longer the period of calorie restriction, the greater the adverse effects on metabolism. The result is better known as yo-yo dieting.
With intermittent fasting, on the other hand, the body does not go into energy-saving mode. After no energy is supplied at all, it must instead mobilize stored energy.
Why you don’t collapse overtired during fasting will explain the hormonal system.
Myth #3: Intermittent Fasting Slows Down the Metabolism
The idea that many small meals could boost metabolism came from the notion that fewer meals per day should slow it down.
In contrast, scientists already debunked this sticky myth more than 50 years ago by showing that fasting instead boosts metabolism (Drenick et al. 19649).
Thus, nature has provided for difficult times. Would there still be humankind today if our ancestors had immediately gone limp due to an unsuccessful hunt? Most likely not!
Due to the increased release of growth hormones, noradrenaline, and adrenaline, our ancestors could search for food longer when it was scarce.
Therefore, the hormonal system ensures that the basal metabolic rate remains high precisely when no energy is supplied (Zauner et al. 200010).
In addition, norepinephrine and epinephrine significantly help break down stored body fat (Patel et al. 200211).
By mobilizing necessary energy while conserving muscle mass, species survival could be ensured (Ho et al. 198812).
Myth #4: Intermittent Fasting Causes Muscle Loss
Contrary to popular myths, fasting does not cause muscles to atrophy.
The myth that fasting destroys muscle arose because protein can be broken down and used for energy when fasting for a sufficiently long time.
However, this is not muscle protein. Instead, the body focuses on defective proteins, for example, in the skin or intestinal mucosa.
In this way, the body obtains amino acids that would otherwise be supplied with food.
In fact, many of our metabolic pathways are designed to conserve muscle mass at all costs.
Also, the efficient fat-burning mechanism of fasting (ketosis) helps prevent muscle breakdown (Paoli et al. 201914).
Besides, the body releases so-called counter-regulatory hormones ensuring muscle mass remains intact during fasting.
One of these is the human growth hormone. During fasting, the release of growth hormone peaks to make sure you don’t lose muscle mass.
For this reason, fasting is also a time-honored strategy for building muscle and is by no means a foreign concept in bodybuilder circles.
Since the natural release of growth hormones decreases with advancing age, intermittent fasting is increasingly crucial for muscle gain.
Yet intermittent fasting protects against muscle loss and bone mass from degeneration (Rudman et al. 199015).
Moreover, the increased release of growth hormone improves muscle recovery after exercise, organ health, and life expectancy in general (Besson et al. 200316).
Myth #5: Your Body Can Only Use a Certain Amount of Protein per Meal
The idea that you need to eat protein every few hours and consume about 30 grams of protein at every meal to build muscle is simply false.
Studies show that more frequent protein intake does not affect muscle mass development (Arnal et al. 200017).
On the contrary, it is the total amount of protein consumed that matters and not the number of meals over which it is distributed.
In fact, a study conducted on older women states that protein intake in large meals is more effective than spreading the same amount of protein over small meals (Arnal et al. 199918).
Ultimately, the human body can absorb more significant amounts of protein at one time or store nutrients.
Because you can keep your insulin levels low longer, intermittent fasting is a method that can promote fat loss and muscle gain at the same time.
That’s why 16/8 intermittent fasting is also known as the Lean Gains Method. In bodybuilding, it has been used for decades to build muscle without gaining body fat precisely.
Myth #6: Fasting Induces Dangerously Low Blood Sugar Levels
In a world dominated by refined carbohydrates and sugar, it is an advantage that intermittent fasting can lower blood sugar.
However, myths evolved that the lower blood sugar induced by fasting could cause even fainting.
Nevertheless, according to research results, the blood sugar level remains stable even if you fast for a more extended period (Merimee et al. 197419).
Accordingly, several protective mechanisms are in line to guarantee healthy blood sugar.
On the one hand, there are the body’s carbohydrate stores in the liver and muscle mass. As long as this stored glycogen is present, the body uses it and converts it back into glucose.
Since full glycogen stores provide about your entire daily energy needs, they slowly become empty after 24 hours, at which point the body must start to tap into stored fat for energy (Anton et al. 201720).
Finally, the so-called winter flab also has a function that has always ensured the survival of our species.
Except for the brain, all organs can be entirely supplied by fat energy sources. However, it is not true that the brain is exclusively dependent on glucose, as we will learn shortly.
When carbohydrate stores are empty, gluconeogenesis kicks in. This process describes the conversion of glycerol, lactate, and amino acids into glucose to ensure that blood glucose levels cannot become dangerously low (Melkonian et al. 202021).
For this reason, essential carbohydrates do not exist, as we do not need them for survival.
Since gluconeogenesis establishes stable blood glucose, intermittent fasting helps eliminate mood swings. These originate from the blood sugar roller coaster that high carbohydrate diets cause.
Contrary to popular belief, it is not intermittent fasting, but the blood sugar crash following a food-induced blood sugar spike causing short-term hypoglycemia.
Myth #7: The Brain Needs a Regular Supply of Dietary Glucose
Also, about 75% of the brain’s energy supply can be fed by fat energy yields because these so-called ketones can cross the blood-brain barrier (Hallböök et al. 201422).
They are also the reason why people report increased mental clarity when fasting. Ketones are a kind of superfood for the brain.
Because the brain and other organs can use ketones more efficiently than carbohydrates, many people report improved mental clarity, mood, and reduced appetite in a state of ketosis (LaManna et al. 201023).
In addition, ketones have antioxidant and anti-inflammatory properties that help repair those cellular damages caused by refined carbohydrates and vegetable oils (Cannataro et al. 201924; Kim et al. 201925).
The liver provides the remaining 25% glucose needed to the brain through gluconeogenesis.
Myth #8: Intermittent Fasting Causes Nutrient Deficiencies
That fasting could lead to a nutrient shortage is a legitimate concern. To examine this fear, we need to look at the spectrum of nutrients we might be lacking:
People think primarily of vitamin deficiencies. However, it is almost impossible to cause a vitamin deficiency through intermittent fasting due to the eating period. However, optional vitamin supplementation is conceivable during highly long periods of therapeutic fasting.
For example, doctors used a multivitamin in the fasting world record over 382 days. Although the researchers also added potassium externally for a short period, they concluded that this was unnecessary.
Only after 200 days of fasting was an increased excretion of minerals detected. These were the electrolytes magnesium, sodium, potassium, and calcium (Stewart et al. 197326).
With intermittent fasting, however, it is only the loss of sodium during the depletion of carbohydrate stores that can cause side effects such as headaches.
However, drinking mineral water or homemade sole water can help.
Regarding macronutrients, it is apparent that we cannot develop a carbohydrate deficiency since there are no essential carbohydrates.
On the contrary, essential amino and fatty acids must be supplied through food. However, the body’s ambition to recycle fats and proteins increases as fasting progresses.
Accordingly, it excretes successively less through stool. But the body goes even further and recycles defective cell parts through autophagy, delivering numerous health benefits and a Nobel Prize (Levine et al. 201727).
Nevertheless, it is always a plus to supply high-quality fats and proteins before and after fasting. For this reason, low-carb diets such as the keto diet have proven to be effective when fasting.
Myth #9: Intermittent Fasting Makes You Hungry and Overeat
One piece of dietary advice that is still widely held is that we should never miss a meal.
The motivation for this advice is that skipping a meal could cause overeating at the following food intake.
Fortunately, with this in mind, studies have been conducted to give us insight into this claim.
On the one hand, although this will indeed cause the next meal to be larger, the total energy intake remains below the result of eating all the day’s regular meals.
After subjects fasted for an entire day, their caloric intake increased from 2,436 to 2,914 the next day, but in contrast, their regular overall caloric intake would have been double the first value.
That’s 4,872 calories. The bottom line in food intake was a deficit of about 2,000 calories.
Beyond that, the researchers had to conclude in the context of this study that fasting could not release unconditioned cravings, as many humans assume (Johnstone et al. 200228).
In my experience, the body also adapts to the new rhythm of food intake during intermittent fasting, putting the size of meals into perspective.
In summary, fasting does not overwhelm you with hunger, as many people assume.
Accordingly, researchers at the University of Vienna have shown that the hunger hormone ghrelin steadily decreases during fasting.
When we are accustomed to ingesting food, ghrelin release increases in a pulsatile manner.
According to scientists, ghrelin causes weight gain through increased food intake and impaired fat utilization (Natalucci et al. 200529).
Myth #10: Breakfast Is the Most Important Meal of the Day
Over the years, we have learned daily routines and, with them, eating habits.
This fact is especially true for morning hunger. Therefore, contrary to popular belief, breakfast is the most important meal of the day for the food industry but not humankind.
When time is short, it is ultimately easier to reach for convenience foods.
Most people believe that skipping breakfast can lead to excessive hunger, lack of concentration, and weight gain. Hence, this is one of the most persistent myths arguing against intermittent fasting.
But otherwise, you’ll lack energy for the day, right?
Not really. When we wake up in the morning, the body elevates adrenaline, glucagon, growth hormone, and cortisol levels, which provide enough energy to start the day (Wüst et al. 200030).
Therefore, it is just after waking up that it is least necessary to supply energy.
A 16-week study with 283 overweight people confirmed this by not observing weight gain in any individual skipping breakfast (Dhurandhar et al. 201431).
However, due to the functioning of our hormone system, this result is logical. By eating breakfast, you shorten the fasting period from 16 to a maximum of 12 hours.
Therefore, insulin levels rise again earlier, leaving the body less time to burn fat for energy.
In addition, fat-burning efficiency correlates with the length of the fasting period.
These are good reasons to forgo breakfast. Besides, in my experience, you’ll have unlearned morning hunger in no more than two weeks anyway.
Science Debunks Numerous Intermittent Fasting Myths
Intermittent fasting is a terrible habit for the food industry. Therefore intermittent fasting myths about meal frequency, particularly, continue to be cheerfully propagated, despite numerous studies busting them.
Neither do smaller, more frequent meals crank up the metabolism nor do they help you lose weight.
Moreover, fasting does not abruptly rob us of our strength. If that were a fact, humanity would have ceased to exist a long time ago.
It is essential to do proper research before drawing early conclusions about your metabolism and health based on conventional wisdom.
After intermittent fasting restores the natural balance between eating and fasting that we lost in the age of abundance, it can improve numerous aspects of your health.
As evidenced by the science cited above, this spectrum ranges from weight loss to chronic disease prevention to mental health.
Intermittent Fasting Schedule FAQ
Why intermittent fasting is bad?
Intermittent fasting isn’t bad. It’s actually one of the best things you can do for your health, according to science.
Does intermittent fasting actually do anything?
Intervallfasten kurbelt laut Studien den Stoffwechsel an und fördert die FettverbreIntermittent fasting helps you balance hormones, lose weight, and prevent modern diseases.
What is the disadvantage of intermittent fasting?
For most people, the major disadvantage of intermittent fasting is to alter their eating habits. In terms of health, it’s a great thing.
Studies Click to expand!
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