Last updated on July 9th, 2024 at 10:33 am
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Lately, lots of people are trying intermittent fasting. Intermittent fasting is a popular eating pattern involving cycling between fasting and eating. This approach has gained attention due to its potential health benefits such as weight loss, improved insulin sensitivity, increased fat burning, enhanced metabolism, autophagy, reduced inflammation, enhances cognitive function, and potential longevity benefits. In this article, we’ll discuss the solutions to the 16 intermittent fasting side effects, that are intermittent fasting, keto, and vegan friendly.
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16 Potential Intermittent Fasting Side Effects And Their Solution
As a dedicated health and fitness enthusiast, my journey through intermittent fasting has been both enlightening and rewarding.
Through meticulous research, personal experimentation, and a commitment to understanding the intricacies of nutrition, I’ve identified the top solutions to combat the 16 potential intermittent fasting side effects. Moreover, we have added different options that is perfectly suited for our beloved vegan fasters.
1) Fatigue
Intermittent fasting can cause fatigue as a side effect due to various reasons. When we fast, our body’s energy sources, like carbohydrates, get depleted, and it starts relying on stored fat for fuel. This shift can lead to low blood sugar levels, resulting in fatigue.
Additionally, during fasting, our body’s metabolism slows down to conserve energy, which can contribute to feelings of tiredness. As a result, our physical and mental performance may decline, leading to fatigue.
Furthermore, inadequate calorie intake during the fasting period can deprive our body of essential nutrients, such as vitamins and minerals. This nutrient deficiency can affect our energy levels and make us feel tired and sluggish.
Moreover, dehydration can occur during fasting if we don’t drink enough fluids. Dehydration can cause fatigue and make it challenging for our body to function optimally.
To solve this problem, NutriGenesis Multivitamins got you covered. You can read more about this supplement by clicking the buttons below.
Note: Aside from taking our recommended solution, staying hydrated, getting adequate rest, and consuming nutrient-rich foods during non-fasting periods can help alleviate these symptoms. If weakness persists or becomes severe, it is recommended to seek suggestions from a healthcare professional for further evaluation.
2) Nausea
Intermittent fasting can cause nausea as a side effect due to several reasons. Firstly, when we fast, our body goes without food for an extended period, which can lead to low blood sugar levels. Low blood sugar can trigger feelings of dizziness, weakness, and, in some cases, nausea.
Secondly, fasting can cause dehydration, especially if we don’t consume enough fluids during the fasting period. Dehydration can result in nausea and discomfort.
Additionally, fasting can disrupt our normal eating patterns, leading to changes in the digestive process and hormone levels. This disruption can cause an upset stomach and feelings of queasiness.
Moreover, when we consume food after a fasting period, our digestive system may react sensitively, resulting in nausea. This reaction can be more pronounced if we consume a large or heavy meal after fasting.
Lastly, some individuals may experience gastrointestinal issues, such as acid reflux or gastritis, which can be exacerbated by fasting, leading to nausea.
To solve this problem, Performance Lab Prebiotic and Vegan Probiotics Digestion Supplement (30 Billion CFUs) got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, staying hydrated, getting adequate rest, and consuming nutrient-rich foods during non-fasting periods can help alleviate these symptoms. If weakness persists or becomes severe, it is recommended to seek suggestions from a healthcare professional for further evaluation.
3) Headache
Intermittent fasting, a popular eating pattern, can occasionally lead to headaches as a side effect. The reason behind this is straightforward. When we fast, our body goes through changes in its hormonal balance and energy levels. These shifts can trigger headaches in some individuals.
During fasting, our body experiences a decrease in blood sugar levels. This drop prompts the release of stress hormones, such as cortisol and adrenaline, to help maintain steady blood sugar levels. However, these hormonal fluctuations can affect blood vessels in the brain, leading to headaches.
Additionally, fasting can result in dehydration, especially if adequate water intake is neglected. Dehydration can also contribute to headaches. When we fast, we may unintentionally reduce our fluid intake, leading to inadequate hydration and subsequent headache development.
To solve this problem, Elm & Rye Magnesium Supplement and FutureKind Vegan Chelated Magnesium Supplement got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, staying hydrated, getting adequate rest, and consuming nutrient-rich foods during non-fasting periods can help alleviate these symptoms. If weakness persists or becomes severe, it is recommended to seek suggestions from a healthcare professional for further evaluation.
4) Feeling weak
Intermittent fasting can cause weakness as a side effect. When we fast, our body’s main source of energy, glucose, becomes limited. As a result, our body starts using stored fats for fuel, which leads to the production of molecules called ketones. While ketones can provide energy, they may not be as efficient as glucose.
During fasting, our body goes through a period of adjustment as it switches from using glucose to ketones. This transition can cause temporary weakness and fatigue. Additionally, our body’s glycogen stores, which are a stored form of glucose, gradually get depleted during fasting, further contributing to feelings of weakness.
Moreover, fasting can also impact our blood sugar levels. When we eat regularly, our body maintains stable blood sugar levels. However, during fasting, blood sugar can drop, leading to feelings of lightheadedness and weakness.
To solve this problem, Elm & Rye Electrolyte Drink Mix Bag and Elm & Rye Electrolyte Gummies got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, staying hydrated, getting adequate rest, and consuming nutrient-rich foods during non-fasting periods can help alleviate these symptoms. If weakness persists or becomes severe, it is recommended to seek suggestions from a healthcare professional for further evaluation.
5) Dizziness
Intermittent fasting can cause dizziness as a side effect due to several reasons. When we fast, our body’s energy stores become depleted, and this can lead to a drop in blood sugar levels. Hypoglycemia, commonly known as low blood sugar, can result in feelings of dizziness, weakness, and lightheadedness.
Additionally, during fasting periods, our body may experience dehydration. We need to consume food and water for an extended period to maintain our hydration levels. Dehydration can cause dizziness and a general feeling of being unwell.
Moreover, when we fast, our body goes through hormonal changes. These changes can affect blood pressure regulation. A sudden decrease in blood pressure can trigger dizziness and fainting spells.
To solve this problem, Elm & Rye Electrolyte Drink Mix Bag and Elm & Rye Electrolyte Gummies got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s important to note that dizziness may vary in severity and duration depending on an individual’s overall health, previous medical conditions, and the duration of the fasting period. Staying hydrated, getting adequate rest, and consuming nutrient-rich foods during non-fasting periods can help alleviate these symptoms. If weakness persists or becomes severe, it is recommended to seek suggestions from a healthcare professional for further evaluation.
6) Slow thyroid
Intermittent fasting can cause a slowdown in thyroid function as a side effect. The reason behind this is that when we fast for extended periods, our body perceives it as a time of scarcity. As a result, it tries to conserve energy by reducing the metabolic rate, which includes slowing down thyroid activity.
The thyroid gland plays a crucial act in regulating metabolism. It produces hormones that control how our body uses energy. However, during fasting, the body enters a state of energy conservation, and the thyroid responds by producing fewer hormones. This slowdown in thyroid function can lead to a decrease in overall metabolic rate.
To solve this problem, Elm & Rye Sea Moss and FutureKind Vegan Iodine Supplement – Liquid Drops got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s important to note that this effect is not permanent and typically occurs in individuals who practice prolonged or extreme forms of intermittent fasting. Most people experience temporary changes in thyroid function, and it returns to normal once regular eating patterns are resumed. If you are concerned about the potential impact of intermittent fasting on your thyroid, it’s recommended to discuss it with a healthcare professional who can give personalized guidance based on your specific needs and health conditions.
7) Hair loss
Intermittent fasting, when practiced improperly, can lead to hair loss as a side effect. This occurs due to several reasons. Firstly, when we fast, our body’s energy resources are limited, and it prioritizes vital functions over non-essential ones like hair growth. As a result, hair follicles receive fewer nutrients and may enter a resting phase, leading to temporary hair shedding.
Moreover, prolonged periods of fasting can cause nutrient deficiencies, particularly in protein, iron, biotin, and zinc. These nutrients are very important for healthy hair growth. Insufficient intake may weaken the hair structure and hinder its growth cycle, leading to hair loss.
Another factor is the potential increase in stress levels during fasting. Stress hormones like cortisol can negatively impact the hair follicles, leading to hair thinning or shedding.
To solve this problem, Saint Felix Hair and Skin Gummies got you covered. You can read more about this supplement by clicking the button below.

Note: Aside from taking our recommended solution, it is crucial to ensure a balanced diet during eating windows, rich in essential nutrients. Consulting a healthcare professional or a registered dietitian can provide personalized guidance to address any potential nutrient deficiencies and minimize the risk of hair loss.
8) Kidney stone
Intermittent fasting, when practiced incorrectly, can potentially lead to kidney stones as a side effect. Kidney stones are solid formations that develop in the kidneys and can cause severe pain.
During fasting, the body may undergo changes in urine composition, particularly an increase in substances that promote stone formation. This can occur due to dehydration, which is often associated with fasting. When the body lacks sufficient fluid intake, urine becomes concentrated, and certain minerals, such as calcium and oxalate, may crystallize and form stones.
Additionally, fasting can affect the levels of certain hormones and electrolytes in the body, such as calcium and citrate, which play a role in kidney stone formation. Imbalances in these substances can contribute to the formation of stones.
To solve this problem, you just need to drink an adequate amount of water, especially lemon water. To learn more about this, you can watch the video below.
Note: To minimize the risk of kidney stones while practicing intermittent fasting, it is crucial to drink an adequate amount of water or other fluids to maintain proper hydration. Including foods rich in citrate, like citrus fruits, may also be beneficial. It is advisable to seek advice from a healthcare professional before starting any fasting regimen to ensure it is done safely and with consideration for individual health conditions.
9) Keto flu
Intermittent fasting can cause flu-like symptoms as side effects. When we engage in intermittent fasting, our body goes through a period of not consuming food for extended periods. During this time, the body adjusts its energy sources and undergoes various metabolic changes.
One reason for flu-like symptoms is that intermittent fasting can trigger a state called ketosis. This is the state where the body starts burning fat for energy instead of glucose. While this is a normal process, it can cause temporary side effects such as headaches, fatigue, and nausea, which resemble flu symptoms.
Additionally, when we fast, our immune system may become temporarily weakened. With regular nourishment, the body may have enough resources to maintain optimal immune function. As a result, we may become more susceptible to infections, including flu viruses.
To solve this problem, Elm & Rye Electrolyte Drink Mix Bag and Elm & Rye Electrolyte Gummies got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it is important to note that these symptoms are typically temporary and tend to subside as the body adapts to the fasting routine. Staying well-hydrated, consuming nutrient-rich meals during eating windows, and gradually easing into fasting can help minimize these side effects. If flu-like symptoms persist or worsen, consulting a healthcare professional for further evaluation and guidance is recommended.
10) Cold
Intermittent fasting can cause cold-like symptoms as a side effect due to certain physiological changes that occur during the fasting period. When we fast, our body undergoes a process called autophagy, where it clears out damaged cells and replaces them with new ones. This rejuvenation process can temporarily weaken our immune system, making us more susceptible to infections such as the common cold.
Moreover, fasting can lead to a decrease in the formation of mucus, which helps to protect our respiratory system from viruses and bacteria. When the mucus levels are reduced, it becomes easier for pathogens to enter our airways and cause respiratory infections.
Furthermore, during the fasting state, our body may experience a drop in blood sugar levels. Low blood sugar can weaken the immune system, making it harder for our body to fight off infections and viruses.
To solve this problem, Elm & Rye Sea Moss and FutureKind Vegan Iodine Supplement – Liquid Drops got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s important to note that these cold-like symptoms are usually temporary and should subside as the body adjusts to the fasting routine. To minimize the risk of catching a cold while fasting, it is advisable to maintain good hygiene, stay hydrated, and ensure a balanced diet during non-fasting periods to support the immune system.
11) Diarrhea
Intermittent fasting can lead to diarrhea as a potential side effect. When you fast, your body undergoes certain changes that can affect your digestive system. One possible reason is that fasting alters the balance of bacteria in the gut, inducing an imbalance known as dysbiosis. This disruption can lead to diarrhea.
Additionally, during the fasting period, your body produces more bile to break down stored fats. Excess bile can stimulate bowel movements and result in loose stools or diarrhea. Moreover, fasting can increase the production of digestive enzymes, which can speed up the digestion process and lead to diarrhea.
Dehydration is another factor to consider. When you fast, it’s crucial to stay properly hydrated. Insufficient water intake can cause dehydration, which can, in turn, result in diarrhea.
To solve this problem, Performance Lab Prebiotic and Vegan Probiotics Digestion Supplement (30 Billion CFUs) got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s important to stay hydrated by drinking enough water. Gradually easing into fasting and ensuring a balanced diet during the eating window can also help maintain a healthy digestive system. If diarrhea persists or becomes severe, it is advisable to consult a healthcare professional for guidance.
12) Nightmares
Intermittent fasting, when practiced properly, can have numerous health benefits. However, it’s worth noting that some individuals may experience nightmares as a side effect. There are a few reasons why this can occur.
Firstly, intermittent fasting involves prolonged periods of not consuming food. When we fast, our blood sugar levels can drop, which can affect brain activity and lead to more vivid dreams, including nightmares.
Secondly, fasting triggers changes in hormone levels, particularly an increase in cortisol, which is known as the stress hormone. Elevated cortisol levels can disrupt sleep patterns and contribute to the occurrence of nightmares. Lastly, fasting can also disrupt the balance of neurotransmitters in the brain, such as serotonin. Reduced serotonin levels may result in mood changes and disturbances in sleep, potentially leading to nightmares.
To solve this problem, NutriGenesis Multivitamins got you covered. You can read more about this supplement by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s important to note that not everyone experiences nightmares during intermittent fasting, and the severity and frequency of nightmares can vary among individuals. Staying well-hydrated, maintaining a balanced diet during eating periods, and ensuring adequate sleep can help minimize the likelihood of experiencing nightmares as a side effect of intermittent fasting.
13) Brain fog
Intermittent fasting is known to cause brain fog as one of its side effects. Brain fog refers to a state of mental confusion, difficulty concentrating, and feeling sluggish or mentally foggy. When we fast, our body experiences a lack of energy from food, which can affect our brain function.
During fasting, the body switches to using stored glycogen for energy. As the glycogen levels decrease, the brain may not receive enough glucose, its primary fuel source. This process can lead to a drop in brain function, resulting in brain fog. Additionally, fasting can disrupt the balance of dopamine and serotonin, which can further contribute to brain fog.
Moreover, fasting can cause dehydration if an individual doesn’t consume enough fluids. Dehydration can lead to reduced blood flow to the brain and impair cognitive abilities. Lack of essential nutrients during fasting periods may also contribute to brain fog.
To solve this problem, Performance Lab MCT Oil got you covered. You can read more about this supplement by clicking the orange button below.

Note: Aside from taking our recommended solution, it is essential to stay hydrated, consume nutrient-rich foods during eating windows, and ensure adequate rest. Additionally, gradually easing into fasting and monitoring the body’s response can help identify any adverse effects and adjust the fasting routine accordingly.
14) High cholesterol
When intermittent fasting is done incorrectly or excessively, it can cause high cholesterol levels as a side effect. This happens for various reasons. Firstly, while fasting, the body releases stored fat for energy, leading to the release of free fatty acids into the bloodstream. These fatty acids can contribute to the accumulation of LDL cholesterol, usually known as “bad” cholesterol.
Furthermore, prolonged fasting can result in the breakdown of muscle tissue for energy. Consequently, the liver produces more cholesterol to compensate for the loss of muscle mass. This excessive cholesterol production can raise overall cholesterol levels, including LDL cholesterol.
Additionally, individuals who practice intermittent fasting may be tempted to consume unhealthy, high-fat foods during their designated eating periods, further increasing cholesterol levels. Diets rich in processed and fatty foods can elevate LDL cholesterol and triglyceride levels.
To solve this problem, Performance Lab Prebiotic and Vegan Probiotics Digestion Supplement (30 Billion CFUs) got you covered. You can read more about these supplements by clicking the buttons below.
Note: Aside from taking our recommended solution, it is crucial to practice balanced intermittent fasting, maintain a healthy diet, and engage in regular physical activity. Seeking guidance from healthcare professionals or registered dietitians can provide personalized advice and ensure that cholesterol levels remain in a healthy range.
15) Insomnia
Intermittent fasting can cause insomnia as a side effect due to various reasons. Firstly, when you fast, your body goes through a period of adjustment where it expects food during certain times. This can interfere with your regular sleep patterns and create challenges in both falling asleep and staying asleep throughout the night.
Secondly, fasting can lead to increased levels of hunger hormones such as ghrelin, which can stimulate wakefulness and make it harder to sleep. Additionally, low blood sugar levels during fasting can initiate the release of stress hormones like cortisol, which can interfere with your sleep cycle.
Furthermore, if you consume caffeinated beverages or stimulants to suppress your appetite during fasting, it can further disrupt your sleep. Caffeine can stay in your system for several hours, making it difficult for you to wind down and fall asleep when it’s time for bed.
To solve this problem, Performance Lab Sleep got you FutureKind Vegan Sleep Aid Supplement covered. You can read more about this supplement by clicking the orange button below.
Note: Aside from taking our recommended solution, it is advisable to adjust your fasting schedule, allowing your body more time to adapt gradually. Additionally, avoiding caffeine and maintaining a balanced diet during non-fasting periods can help regulate your sleep and minimize the risk of insomnia. Consulting a healthcare professional for personalized guidance is always recommended.
16) Gout
There are various reasons why intermittent fasting can lead to gout as one of its side effects. When you fast, your body goes into a state of burning stored fat for energy called ketosis. This releases ketones and increases the production of uric acid, which causes the formation of urate crystals in the joints. Gout, a type of arthritis, is caused by these uric acid crystals building up in the joints and triggering gout attacks.e
Moreover, fasting can cause dehydration, which concentrates uric acid in the body. Dehydration reduces urine volume, leading to increased uric acid levels in the blood and a higher risk of gout flare-ups. Additionally, fasting can lead to weight loss, and sudden weight loss is associated with a greater risk of gout. When fat cells break down, they release stored uric acid, further contributing to elevated uric acid levels.
To solve this problem, NutriGenesis Multivitamins got you covered. You can read more about this supplement by clicking the buttons below.
Note: Aside from taking our recommended solution, it’s critical to drink plenty of water to stay hydrated, limit the consumption of foods rich in purines (like organ meats and seafood), and maintain a healthy weight. Seeking advice from a healthcare professional is advisable for personalized guidance and monitoring of uric acid levels.
FAQs
What are the negatives of intermittent fasting?
Intermittent fasting can lead to negative effects like increased hunger, irritability, and difficulty concentrating, especially during the fasting period. It may also cause nutrient deficiencies if not planned properly, and for some, it can disrupt their social life or lead to disordered eating habits.
Is it bad to intermittent fast everyday?
Intermittent fasting every day can be safe for many people, but it’s not suitable for everyone. Doing it daily might increase the risk of nutrient deficiencies or lead to unhealthy eating patterns. It’s crucial to listen to your body and consult with a healthcare professional if you have concerns.
What happens to your body when you fast for 16 hours?
When you fast for 16 hours, your body shifts into a state called ketosis, where it starts burning stored fat for energy. This can lead to weight loss. Additionally, your insulin levels drop, which may improve insulin sensitivity and reduce inflammation in the body.
What are the side effects of 16 hour intermittent fasting?
Some people may experience side effects like headaches, fatigue, or dizziness, especially when starting intermittent fasting. These symptoms usually improve as your body adjusts to the new eating pattern. Staying hydrated and consuming balanced meals during eating windows can help alleviate side effects.
Is intermittent fasting bad for your heart?
Intermittent fasting may have both positive and negative effects on heart health. While some research suggests it could improve heart health markers like cholesterol levels and blood pressure, excessive fasting or unhealthy eating patterns can have the opposite effect. It’s essential to maintain a balanced diet and consult with a doctor if you have heart concerns.
Do you eventually stop losing weight with intermittent fasting?
Initially, many people experience weight loss with intermittent fasting. However, weight loss may plateau over time as the body adapts to the new eating pattern. To overcome this plateau, it’s important to reassess your diet, exercise routine, and consider consulting a healthcare professional for personalized advice.
How do you know if you should stop intermittent fasting?
You should consider stopping intermittent fasting if it negatively impacts your physical or mental health. Signs to watch for include extreme hunger, fatigue, mood swings, or disrupted sleep patterns. If you experience persistent side effects or discomfort, it’s essential to reassess your approach or consult with a healthcare professional.
Why am I not losing weight on 16 8 fasting?
If you’re not losing weight with a 16/8 fasting schedule, several factors could be at play. You might be consuming too many calories during your eating window, not getting enough physical activity, or experiencing metabolic changes. Reevaluating your diet, exercise routine, and consulting a healthcare provider can help address these issues.
How long do intermittent fasting side effects last?
Side effects of intermittent fasting typically last for a few days to a few weeks as your body adjusts to the new eating pattern. Common side effects like headaches or fatigue often diminish over time. However, if you experience severe or prolonged side effects, it’s essential to seek medical advice.
Why is 16 hours the magic number for fasting?
The 16-hour fasting window is often considered effective because it allows the body to deplete its glycogen stores and enter into a state of ketosis, where it burns fat for energy. This duration also aligns with natural circadian rhythms, potentially enhancing metabolic processes and promoting weight loss.
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Ali Webster is a seasoned researcher, communicator, and Registered Dietitian with a diverse background encompassing government, nonprofits, academia, and health care. The core belief is that science should be made accessible, understandable, and relevant to all individuals, driving the motivation behind their work. Proficient in conducting and interpreting research to shape nutrition policy decisions, the individual also excels in nutrition and health communication, consumer research survey development and implementation, and clinical nutrition. Holding a Doctorate of Philosophy with a focus on Nutrition and Epidemiology from the University of Minnesota, their dietetic internship emphasized medical nutrition therapy.