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Home arrow Nutrition arrow Intermittent Fasting arrow Fasting Headache and How to Get Rid of It

Fasting Headache and How to Get Rid of It

Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 15, 2023
3 min read 2030 Views 0 Comments
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While fasting can have several health benefits, it can also lead to various side effects, including headaches. Fasting headaches are a common complaint among individuals who fast, and they can range from mild discomfort to severe pain. How to deal with them?

fasting headache

When you start fasting, your body goes through a lot of changes. Some people get more tired than usual; some people get more energy than before. Not to mention all of the health benefits your body receives while fasting.

There is, however, a thing known as a fasting headache, and plenty of people have experienced this particular phenomenon. 

We’ve talked with expert doctors to explain fasting headaches and how to best deal with them.

Fasting Headache: Is It Common?

Fasting headaches are a very common side effect of intermittent fasting, especially when you are fasting for long periods of time. For most people, a fasting headache can be mild or moderate in intensity.

Someone who has a fasting period of 16 or 18 hours will typically start to feel a headache pain starting around the 16-hour mark. Even after eating again, however, this pain can last up to 72 hours.

Symptoms of Intermittent Fasting Headaches

How do you know what you’re feeling is an intermittent fasting headache? 

People can get headaches from many things: low blood sugar, tension, migraine, etc. 

Here are some ways to determine the precise cause of your headache:

#1 Mild to moderate pain

Intermittent fasting headaches tend to not be as painful or debilitating as a migraine. 

The pain that you feel when you start getting a headache due to intermittent fasting will most likely be tolerant or easily managed with pain medication.

#2 Pain located at the forehead

The location of a headache can tell you a lot about what’s causing it. For an intermittent fasting headache, you’re going to feel the pain located centrally in the forehead, rather than behind the eyes or around the whole head. It’ll feel much like a tension headache.

#3 Steady pain

Another way to know what the pain you’re feeling is an intermittent fasting headache is the way the pain presents.

A fasting headache will not throb like other headaches. The pain will be steady, sometimes increasing in intensity as time goes on.

What Can Cause a Headache While Fasting?

While the exact causes of a headache while intermittent fasting is still relatively unknown, doctors have come up with several reliable theories as to why this happens.

#1 Dehydration

Sometimes, during intermittent fasting, people forget to drink as much water as they need to. Dehydration can quickly cause headaches, especially in people who are practicing intermittent fasting.

#2 Caffeine withdrawal

Once you start intermittent fasting, your body goes into a full detox. Many doctors think that a fasting headache occurs when the body starts going into caffeine withdrawal, especially if you’re someone who drinks a lot of soda throughout the day.

#3 Low blood sugar

Blood sugar levels have a lot to do with keeping a headache at bay. If you’re experiencing this unpleasant side effect of fasting, it’s possible that your blood sugar is dropping.

Make sure to keep track of your normal blood sugar levels to rule this out.

How to Deal With Headaches During Fasting?

Now that we know the most common possible causes of headaches during intermittent fasting, let’s take a look at how to alleviate the pain for headache sufferers. 

#1 Drink more water

Fasting protocol 101 states that you should drink water and stay hydrated. If you’re not getting enough water, then your overall health will suffer, not just your head!

As much as 30% of our water supply comes from what we eat, so you need to up your water intake.

#2 Reduce your carbs

Before your eating window, consider switching over to a low-carb diet with nutrient-dense foods.

This will ensure that your blood sugar levels aren’t fluctuating wildly as they drop from having a carb and sugar-rich last meal before going on a 16-hour fast.

#3 Reduce your caffeine intake

In order to avoid caffeine withdrawal, try reducing how much caffeine you have in the days leading up to your fast. This will help those who experience headaches due to their bodies craving caffeine.

#4 Take it easy

Last but not least, try not to do any high-energy activity. You’re at a higher risk of getting a fasting headache if you’re expending energy while your body has a lowered food intake. Stress can also be a key cause of headache disorders.

A Word From Our RD

Healthcare professionals can’t stop singing the praises of intermittent fasting as a way to lose weight, regulate things like heart disease, and help people lower their risk of type 2 diabetes.

People have been fasting all of the time, both for health benefits and religious reasons. When fasting, the body goes through a lot of different changes, and some of these can be unpleasant to deal with.

A good way to make sure your body is prepared for fasting so that you don’t end up with fasting headaches is to never skip meals, be aware of low blood sugar, and keep an eye out for all of the symptoms of fasting headaches.

However, keep in mind that you may have any number of headache disorders that have little to do with fasting. If your fasting headaches feel more like a migraine, make sure to contact your doctor for professional medical advice.

Get enough sleep, eat nutrient-rich meals, and make sure to manage your stress! These will all help your brain rest and help avoid these headaches.


Intermittent fasting is a great tool for weight loss, but many people suffer from a fasting headache attributed to these fasting periods. 

While doctors don’t know the exact cause, there are some theories: it could be low blood sugar or even dehydration.

These tips and tricks will help make sure that your fasting goes smoothly. Stay hydrated, avoid a diet that will give you low blood sugar levels during your fast, and slowly reduce your caffeine to avoid withdrawal.

Written by Thalia Oosthuizen
Thalia has always wanted to be a writer, starting her first local newspaper at the age of 11. She also has enjoyed a passion for health and fitness since a young age, playing many sports through her schooling career, and still enjoys biking, running, and swimming today. She studied English Language at University for 3 years, developing a passion for spelling, grammar, and research. She now has over 10 years of experience writing, proofreading, and editing, and has paired this with her love for health and fitness by writing health content.
The article was fact checked by Rosmy Barrios, MD
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Written by Thalia Oosthuizen
Fact checked by Rosmy Barrios, MD
Last update: October 15, 2023
3 min read 2030 Views 0 Comments

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