7 Common Myths About Intermittent Fasting
Medically reviewed and edited by Fasting has gained popularity for its numerous wellness benefits. However, this has also increased the myths and misconceptions surrounding its overall safety.
Many of these myths can make people feel like fasting isn’t the right dietary approach for them.
That’s why it’s important to know what the scientific facts are to help you make an informed decision that will help you achieve your health goals.
In this article, we’ll take a closer look at the most common misconceptions around fasting, and also provide research-based evidence to debunk them.
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Myth #1: Fasting Slows Down Your Metabolism
A common argument against fasting is that it puts your body into starvation mode, which shuts down your metabolism and prevents you from burning body fat.
Some people tend to forget that most weight loss methods can reduce the number of calories burned over time.
There is currently no evidence to suggest that fasting causes higher fat loss than other diets.
In fact, research shows that short-term fasting and reducing your food intake may actually boost metabolism function, which promotes weight loss.
When you fast, the body undergoes a metabolic shift. This is because it shifts from burning glycogen (carbohydrates and sugar) for energy to using stored fat for fuel.
During this transition, there is a significant increase in norepinephrine – a hormone that stimulates metabolism and causes fat cells to break down faster.
This enhances your metabolism and increases the speed at which the body burns fat during an eating window.
Over time, fasting may also improve your metabolic health and reduce your risk of developing digestive disorders.
Myth #2: Fasting Makes You Lose Muscle
Individuals considering fasting may be concerned about the idea that fasting causes muscle loss that may contribute to weight gain.
This results from thinking that decreasing meal frequency may limit the body’s overall ability to support muscle development, leading to a decrease in muscle mass.
Some research suggests that fasting actually preserves lean muscle mass. In some cases, fasting may even stimulate muscle growth.
One of the mechanisms behind this is that fasting periods increase the production of the growth hormones necessary for muscle building and preservation.
Because of this ability to stimulate muscle growth, fasting may be seen as a more sustainable option for maintaining lean mass compared to other weight loss methods.
It’s important to note that fasting may only cause muscle loss when you don’t consume enough protein and nutrient-dense foods in your diet.
Just like with any other diet, the type of exercise you do while fasting also plays a key role in preserving muscle mass.
Strength or resistance training are some of the best workouts for stimulating muscle growth to maintain muscle mass.
Myth #3: Fasting Causes Nutrient Deficiencies
One of the most common misconceptions about fasting is that its lower calorie intake causes nutrient deficiencies, which could harm your overall health.
However, fasting may positively impact nutrient absorption and improve how your body uses them.
Fasting also gives your digestive system valuable periods of rest, which may allow it to function more efficiently.
It’s important to note that just like any other dietary pattern, fasting may put you at an increased risk of developing a nutrient deficiency if you don’t follow a balanced diet.
These deficiencies tend to occur when you don’t plan your meals properly and fail to consume nutrient-dense foods that contain a variety of vitamins and minerals.
You may also develop a deficiency if you implement extreme fasting methods — such as restricting yourself from eating for more than 24 hours at once and skipping meals. However, short-term fasting is generally considered safe for most people.
There is currently no evidence to suggest that there is a higher risk of developing nutrient deficiencies when fasting compared to other weight loss methods.
Myth #4: Fasting is Unsafe
Fasting has often been criticized as an unsafe and unhealthy practice, especially by people who are concerned about factors like dehydration and the disruption of bodily functions.
It’s important to note that fasting only becomes unsafe when you follow an extreme cycle of restriction. When practiced sensibly, fasting is safe and offers several health benefits.
There are also a number of things you can do to ensure that you implement fasting responsibly, including:
Maintaining proper hydration: Drinking plenty of fluids during a fasting period is a fundamental part of TRE. Ensuring that you are adequately hydrated helps to prevent weakness and confusion that may occur when you don’t eat for a while.
Take individual precautions: Fasting may not be suitable for everyone — especially pregnant or breastfeeding women, individuals with a history of eating disorders, and people with certain medical conditions. If you fall into any of these categories, consult with a healthcare professional before you start fasting.
Key Point: Does Fasting Impact Exercise Performance?
Fasting can have an effect on exercise performance, but it will vary depending on the timing and duration of the fast.
During a fasting state, glycogen stores — the body's primary energy source during exercise — may become depleted, which may reduce endurance and strength.
However, some individuals who have adapted to fasting may maintain performance levels during workouts — particularly when practicing intermittent fasting or time-restricted eating (TRE).
Fasting can also promote the use of stored fat for energy, which may benefit endurance athletes.
Myth #5: Fasting is Only About Weight Loss
Although one of the benefits of fasting is that it can help you lose weight, it can have a positive effect on many other components of your overall well-being.
Fasting may improve blood sugar control, reduce the risk of neurodegenerative disorders, and protect against medical conditions like cancer.
When implementing fasting, it’s important to determine the goals you want to reach with this dietary approach. This will also help you choose the right fasting type to achieve them.
It’s also important to implement fasting in a way that will ensure long-term sustainability for it to be effective. This means choosing a method that fits into your current lifestyle without disruption.
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Myth #6: Fasting is Harmful to Your Brain
There is a misconception that fasting can be detrimental to your brain health and lead to cognitive decline, impaired mental function, and damage.
However, research has shown that fasting may have positive effects on the brain when practiced sensibly and within reasonable limits.
Some studies even suggest that fasting can improve cognitive function by inducing a biological state called ketosis. This state occurs when the body uses stored fat for energy instead of glucagon.
When the body makes the switch, the brain starts using alternative energy source — called ketones — to function.
Ketones help improve mental clarity by enhancing mitochondrial function and reducing oxidative stress and inflammation that can impair brain function.
Fasting has also been associated with neuroprotective effects, helping the body to prevent diseases like Alzheimer’s and Parkinson's.
It does this by initiating autophagy — a process that removes damaged cells and replaces them with new ones — that can eliminate defective cells from the brain.
Myth #7: There is No Scientific Evidence that Proves Fasting is Effective
Some individuals may question the effectiveness of fasting and wonder if there is enough evidence to support the benefits of this dietary approach.
Numerous studies have demonstrated that fasting can contribute to weight loss, better metabolic and heart health, and improved cognitive functioning.
The important thing to note is that fasting must be implemented in a sustainable manner for it to be effective.
Resorting to extreme measures of restrictive eating can be harmful to your health, and these patterns may indicate a more serious disorder that requires professional help.
Fasting also isn’t a one-size-fits-all approach, which can contribute to the belief that it doesn’t really work.
However, fasting can be adjusted to fit into your lifestyle, so choosing the right method is the first step to reaping its benefits.
Key Point: What is the Best Way to Start Fasting?
Start gradually and use a mindful approach if you’re new to fasting.
For beginners, easing into fasting with intermittent or TRE may be the most beneficial method.
Start by extending the time between your last and first meal, allowing your body to adjust to longer fasting windows gradually.
It’s also essential to ensure that you stay hydrated during fasting periods and listen to your body's hunger and fullness cues.
Consulting with a healthcare professional or registered dietitian before starting a fasting regimen is a good option, too.
They can help you determine the most suitable approach based on your individual needs and goals.
Where Can You Learn More About Fasting?
If you’re concerned about fasting and how it may affect your overall health, LifeMD is here to help.
Our team of medical professionals can assist you with information and provide guidance on fasting — all from the comfort of your home.
Make an appointment with LifeMD to learn more about fasting and healthy ways to manage your weight.
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