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The 9 Potential Intermittent Fasting Side Effects

Intermittent fasting is a term people use to describe patterns of eating that include regular periods of fasting in which they consume very few or no calories.

Studies have linked intermittent fasting to a number of health benefits:

  • weight loss

  • decreased risk factors of heart disease

  • lower blood pressure

  • improved insulin sensitivity

  • reduction in markers of oxidative stress

  • improved blood sugar control

These findings have led to the increased popularity of intermittent fasting regimens like:

  • time-restricted feeding (TRF)

  • alternate-day fasting (ADF)

  • periodic fasting

If you’re interested in trying out intermittent fasting, you’re probably curious to know whether it has side effects.

The short answer: Intermittent fasting is safe for most people. However, intermittent fasting has some negative side effects if you have a poor Metabolism/ relationship with balanced macronutrient food pairing.

1. Hunger and cravings It may be no surprise that hunger is one of the most common side effects related to intermittent fasting. When you reduce your calorie intake or go long periods without taking in calories, you may experience increased hunger. This sets the foundation to over consume on portions when the time comes to eat.

2. Headaches and lightheadedness Headaches are a common side effect of intermittent fasting. They typically occur during the first few days of a fasting protocol. Interestingly, researchers have found that “fasting headaches” are usually located in the frontal region of the brain and that the pain is typically mild or moderate in intensity. What’s more, people who commonly get headaches are more likely to experience headaches during fasting than those who don’t. Researchers have suggested that low blood sugar and caffeine withdrawal may contribute to headaches during intermittent fasting.

3. Digestive issues Digestive issues — including constipation, diarrhea, nausea, and bloating — are symptoms you might experience if you do intermittent fasting. The reduction in food intake that comes along with some intermittent fasting regimens may negatively affect your digestion, causing constipation and other side effects. Plus, changes in diet associated with intermittent fasting programs may cause bloating and diarrhea. Dehydration, another common side effect related to intermittent fasting, can worsen constipation. For this reason, it’s essential to stay properly hydrated while practicing intermittent fasting. 4. Irritability and other mood changes Some people may experience irritability and other mood disturbances when they practice intermittent fasting. When your blood sugar is low, it may cause you to feel irritated. Low blood sugar, or hypoglycemia, can occur during periods of calorie restriction or over periods of fasting. This can lead to irritability, anxiety, and poor concentration.

5. Fatigue and low energy Studies show that some people practicing various methods of intermittent fasting experience fatigue and low energy levels. Low blood sugar related to intermittent fasting can cause you to feel tired and weak. Plus, intermittent fasting may lead to sleep disturbances in some people, which can cause tiredness during the day. 6. Bad breath Bad breath is an unpleasant side effect that can occur in some people during intermittent fasting. This is caused by lack of salivary flow and the rise of acetone in the breath. Fasting causes your body to use fat for fuel. Acetone is a by-product of fat metabolism, so it increases in your blood and breath during fasting. What’s more, dehydration — a symptom associated with intermittent fasting — can cause dry mouth, which may lead to bad breath.

7. Sleep disturbances Some research suggests that sleep disturbances, such as being unable to fall asleep or stay asleep, are among the most common side effects related to intermittent fasting. Fatigue may be more common in the initial days of an intermittent fasting regimen as your body excretes large amounts of salt and water through the urine. This can lead to dehydration and low salt levels, too.

8. Dehydration As mentioned above, during the initial days of fasting, the body releases large amounts of water and salt in the urine. This process is known as natural diuresis or natriuresis of fasting. If this happens to you and you don’t replace the fluids and electrolytes you lost through urine, you could become dehydrated. Additionally, people practicing intermittent fasting may forget to drink or may not drink enough. This may be especially common when you’re first beginning an intermittent fasting regimen. To stay properly hydrated, drink water throughout the day and monitor the color of your urine. Ideally, it should be a pale lemonade color. A dark-colored urine may indicate you’re dehydrated.

9. Malnutrition If not done properly, intermittent fasting can lead to malnutrition. If a person engages in very long fasting periods and doesn’t replenish their body with enough nutrients, this could result in malnutrition. The same goes for poorly planned continuous energy restriction diets . People are generally able to meet their calorie and nutrient needs on various types of intermittent fasting programs. However, if you don’t plan or practice your fasting program carefully over a long time period or you deliberately restrict calories to an extreme level, you might experience malnutrition along with other health complications. That’s why it’s essential to consume a well-rounded, macronutrient dense diet while practicing intermittent fasting. Make sure you never overly restrict your calorie intake.

Ideally, if you do implement intermittent fasting into your diet, it is best recommended to do it around your sleep cycle to reduce any negative effects associated with Intermittent Fasting. The most beneficial part of this comes down to allowing yourself gain as many nutrients within your day and allow your body to use it as fuel for recovery and weight loss while you sleep. To get the most out of your intermittent fasting, maintaining a good caloric intake to support your daily requirements. This means that we NEVER SKIP BREAKFAST, eat breakfast within 45 minutes of waking up, consuming a balanced meal or snack 2-3 hours then after and following through with that until our last meal NO LATER THAN 6-7 pm. Intermittent Fasting will then start after our last meal and we repeat the same schedule the following day.

It is recommended that no matter what day of the week, we strive to maintain consistency and follow this routine to get the most out of your intermittent fasting.

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