Men engage in intermittent fasting for different reasons. However, while fasting promotes a number of health benefits, some side effects associated also exist. If you are considering trying out intermittent fasting, we discuss some common side effects you might experience as your body adjusts to this new diet change.
What Is Intermittent Fasting?
Intermittent fasting, as the name implies, refers to a type of fasting done at regular intervals. Usually, you are supposed to eat within a certain time window before fasting until the designated “eating window” comes again. This time window can range from a couple of hours in a day to even days in a week.
Intermittent fasting refers to a popular type of fast popularly prescribed by different dieticians and health practitioners. Many say it acts as an effective weight loss regimen and also an effective method of monitoring and controlling calorie intake. To learn more about the types of intermittent fasting, check out our article on the best intermittent fasting ratios.
What Are the Side Effects of Intermittent Fasting in Men?
As widely praised as intermittent fasting is, there are just as many claims on the benefits of intermittent fasting. In fact, many describe it as a fad — a popular diet plan that promises quick weight loss without a long-term effect. There exist a lot of side effects associated with intermittent fasting, especially in men advised to take between 2000 and 2500 calories daily.
Here are some common side effects of intermittent fasting:
1. Effect on REM sleep

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Rapid eye movement (REM) is a process you undergo while sleeping. This stage of sleep proves extremely vital for the brain because it affects the mental and learning capacity of a person.
REM sleep has also been shown to have a positive or negative effect on the mood of a person. Intermittent fasting, according to some studies, has been shown to affect the REM sleep pattern, which is a great concern because it can affect brain function. Overall, if the quality of REM sleep is affected, there is a huge possibility of mood disorders occurring.
2. Increase in The Production of Cortisol

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Cortisol, which is also known as the stress hormone, is triggered when a person is exposed to stress. Intermittent fasting is a known trigger of this hormone. Although women possess higher levels of the hormone cortisol than men, fasting can lead to high levels of cortisol in the body regardless of sex.
A high level of cortisol has been associated with irregular blood glucose levels, an increase in blood pressure, and increased fat storage. In turn, irregular blood sugar and blood pressure can result in bouts of nagging headaches. More fat stored in the body can eventually lead to weight gain. Considering that most people fast to lose weight, this counteracts the intent of fasting and can be a major source of discouragement for many looking to shed some pounds.
To find out ways to deal with stress better and lower your cortisol levels, check our article on coping strategies to calm you down.
3. Constant Headaches

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Constant headaches can occur due to the low level of blood glucose in the body from fasting. This is because the brain doesn’t store glycogen and becomes dependent on the glucose from the rest of the body in the process.
When your body digests food, it breaks down carbohydrates into glucose for energy. When there is a low level of blood glucose transported to the brain, change in the pain receptors in the brain takes place which results in buzzing headaches that come and go.
4. Increase in The Production of Stomach Acid

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Intermittent fasting can cause a significant increase in the level of stomach acid produced, which can cause problems on an empty stomach. Normally, the body produces stomach acid just before mealtime to prepare for the digestion of food later on.
However, when a person is fasting and doesn’t eat at a designated time, the body continues to produce stomach acid levels in excess. This can lead to gastric pain and heartburn when the excess stomach acid travels up your esophagus.
5. Dehydration

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According to a number of studies, intermittent fasting can cause severe dehydration if a person doesn’t take fluid or enough fluid. This, in turn, can also result in headaches, dizziness and other symptoms.
This is why it’s highly advised to drink water while fasting to keep yourself hydrated and keep your bodily systems moving. This is known as a water fast, meaning you do not eat or drink anything besides water.
6. Trigger Eating Disorders

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Believe it or not, there are men who have a previous history of any form of eating disorder such as overeating, undereating, anorexia, and bulimia. Intermittent fasting can trigger these disorders which will only end up exacerbating current health problems.
The ultimate goal of intermittent fasting is to help you lose extra pounds and to maintain a healthy weight amount. However, it can cause negative health effects on those who either have a distorted body image or have trouble keeping food down. As such, it should never be pursued by those with unhealthy eating patterns and habits.
Overdoing any form of fasting is extremely dangerous. This is because it deprives you of the nutrients your body needs to maintain energy and to prevent damage to vital organs. When this happens, malnutrition, osteoporosis, and even death can occur. Before pursuing IF, consult with your doctor or nutritionist to make sure that your eating patterns are up to standard and that you’re equipped with the proper tools to monitor your health.
7. Reduction in Muscle Gain

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Muscles use up more calories than fat so men trying to build muscle tend to consume a higher number of calories than what is burnt off during exercise. This replenishes the body with the required amount of calories it needs to sustain itself.
Intermittent fasting restricts your caloric intake, making it harder to build muscle mass. This is why people choose to fast to lose weight gained from fat rather than to bulk up on muscle. To find out how to retain muscle mass through exercise instead, check out our article on basic calisthenics workouts.
8. Dizziness, Lightheadedness, and Fainting

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The above-mentioned symptoms usually occur when prolonged intermittent fasting takes place and eventuates from low levels of electrolytes in the body. But how are intermittent fasting and low electrolyte amounts interrelated?
Obviously, intermittent fasting requires restricting food and sugar intake. When this happens, essential nutrients such as calcium, potassium, and sodium become depleted. As a result, dehydration occurs which results in symptoms such as weakness, dizziness, and confusion. Experiencing these symptoms in open spaces or crowded areas can lead to severe physical injuries which can become fatal.
In order to prevent dehydration while continuing your intermittent fasting routine, make sure to keep your body replenished with the proper nutrients. You can do this by simply drinking enough water, or by consuming beverages such as black coffee or unsweetened tea.
9. Low Temperature

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A person undergoing intermittent fasting may feel cold sensations in the extremities of his body even under normal temperature levels. You might feel cold in the hands and feet, which is a result of the body adapting to low levels of blood glucose.
Changing body temperature is not uncommon especially during irregular weather patterns. However, the effects of IF coupled with cold external temperatures can lead the body to experience hypothermia which, if untreated, can cause a person to go into shock or even to die.
In order to prevent hypothermia while fasting, it’s important to keep your body temperature at optimal levels. You can do this by immersing yourself in temperate conditions, wearing warm layers of clothing, or simply by drinking hot beverages such as boiled water or hot tea.
10. Mood Swings

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The biochemical substances involved in the regulation of appetite also play a role in mood regulation. People who engage in intermittent fasting are often more irritable, which could be due to hunger and a lack of energy, leading to fatigue and grumpiness.
Another cause could be due to the fact that the consumption of certain foods boosts the production of certain neurotransmitters such as serotonin. This hormone plays a vital role in the regulation of negative feelings such as anxiety and depression.
11. Overeating

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Intermittent fasting involves long periods of switching between fasting and non-fasting. During these periods, some people may tend to overeat and binge eat to make up for the hours when they didn’t eat.
Cravings also increase because of intermittent fasting. Thus, people tend to eat more during those “eating windows” to satisfy all their cravings. These actions are counterproductive for people who engage in intermittent fasting to lose weight.
Intermittent fasting has done wonders for many people. Thanks to its various benefits, many have experienced a healthier lifestyle as a result of following its methods. Nevertheless, it’s still important to understand that intermittent fasting, when pursued excessively, can take a toll on one’s physical health.
As such, it’s vital to know the proper ways of monitoring your health should you wish to pursue this routine. Remember that there’s too much of a good thing can be dangerous so before undertaking it, know your limits and don’t push yourself too far.
If you’re just starting out with intermittent fasting, it might help to start a fasting journal to keep track of your goals and any side effects you’re experiencing. You can then use these records to consult your health professional and work through how to resolve them.