Intermittent fasting headache
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Intermittent Fasting Headache

If you're currently on your weight-loss journey, you may have practiced intermittent fasting — a great way to burn that stubborn fat. But can it cause headaches? Yes, in some people.


Any type of intermittent fasting regimen can develop a mild and non-pulsating headache due to many reasons [1]. The most prominent reason is the decrease in overall energy as you fast. It's just like experiencing fatigue and head pain when you skip breakfast or forget to take your meal during a hectic day.


But this is not the only reason! Let's discover why you feel the troublesome pain in your head while fasting and how you can relieve or prevent it.



What are intermittent fasting headaches?


fasting headache


Intermittent fasting means not eating or drinking anything for an entire day or a certain number of hours in a day. You can adopt several forms of intermittent fasting, such as alternating day fasting, twice-a-week method, periodic fasting, and time-restricted eating, to name a few [2].


Not only does it keep your body in shape by burning the fat, but it also regulates insulin levels, cellular growth and repair, and improves immunity against diseases [3]. However, adopting this lifestyle comes with risks — the most prevalent is a "fasting headache."


Usually, the risk of fasting headaches increases with the duration of the fast. You will start experiencing a mild to moderate headache after at least 14-16 hours of fasting [1]. The pain subsides as you re-fuel your brain and body by eating a healthy meal.


The good news is that such headaches typically occur in the first few days of your intermittent fasting regimen [2]. As your body gets used to the new lifestyle, you feel healthier and more active during the fasts.



Symptoms of a fasting headache


  • A fasting headache usually occurs in the frontal region of your head. You will most likely feel mild and non-throbbing pain in the middle and towards the end of your fasting hours. If you're a migraine patient, you will experience an increased frequency of fasting headaches compared to healthy people.
  • A fasting headache may cause you to feel mild nausea.
  • You may feel dizziness and fatigue.
  • Fasting headaches can affect your mood and make you cranky and short-tempered.
  • In addition, you may feel muscle tension in your neck and shoulders.



What causes intermittent fasting headaches?


Tracing the exact cause is not easy as many reasons can trigger the head pains, depending on the individual's conditions. Mentioned here are some major reasons that can be the culprits for your headaches.


1. Low blood sugar levels (hypoglycemia)


As you fast, your body uses up the stored glucose for energy. Some doctors say that a decrease in blood glucose level is the reason behind headaches. Low blood sugar levels, a.k.a hypoglycemia, is a condition where body glucose levels drop below 70mg/gL [4]. It triggers a throbbing head pain that generally accompanies hypoglycemic symptoms of blurred vision, fatigue, nervousness, and increased heart rate.


However, this doesn't explain why people with normal sugar levels experience fasting headaches, which helps us conclude that "fasting headaches are not an easy diagnosis to make!" [5].


Hypoglycemia is a common cause of triggering migraine headaches during fasting. Migraine sufferers sometimes crave a sugary snack right before migraine hits [6]. So, if you feel like snacking on a chocolate bar during fasting, it may just be the onset of a migraine attack.


2. Dehydration


Do you know that dehydration causes your brain to shrink in size? Your brain contracts and moves away from the skull as it loses water, which is why you experience headaches if dehydrated [7].


If you fast for 16 hours or more continuously, you're likely to suffer from dehydration, leading to head pains. Other symptoms of dehydration fasting headaches can include dark-colored urine, dizziness, sleepiness, and cranky mood.


During fasting, as you lose fluids in the form of sweating and excretion, you're also losing essential minerals and electrolytes — a phenomenon called "natural diuresis." Your body organs need different minerals to work in tandem; thus, the loss of minerals can disrupt normal body functions.


In addition, loss of sodium is directly linked to headaches. This condition in its chronic form is known as hyponatremia. Sodium regulates the water around your cells and even a small disruption in its concentration can trigger headaches [8]. 


A word of caution: hyponatremia can be caused by drinking excessive plain water! The safer way is to drink electrolyte solutions or eat sodium-rich foods before fasting.


3. Poor sleep


Are you getting proper sleep during your fasting regimen? If not, then this could be the reason behind your headache. When you fast, your brain becomes more alert than on regular days. You might even feel more productive and focused. This is because of the release of a neurotransmitter called "Orexin-A". A lack of healthful sleep will drain your brain to the point that it will start aching.


poor sleep


In addition, lack of sleep can cause you to have a bad mood. Research conducted at the University of Pennsylvania concluded that even partial sleep deprivation could cause anxiousness, stress, and crankiness [9]. Stress, in turn, is another cause of headaches [10].


According to research, sleep restlessness generally subsides within the first week of your intermittent fasting regimen [11].


4. Caffeine withdrawal


If you're a coffee person, adopting intermittent fasting means you will take a break from your regular caffeine intake. Caffeine withdrawal or going cold turkey can potentially cause headaches after 14-16 hours of the last caffein intake – the same pattern seen in typical fasting headaches [12].


Caffeine narrows your blood vessels, thus reducing blood flow to the brain. Once you stop taking caffeine, the blood resumes its regular flow to the brain, consequently causing short-term withdrawal headaches. Such headaches will subside as soon as your brain gets used to increased blood flow to the brain [13].



How to relieve intermittent fasting headaches?


There's no need to keep suffering from headaches while practicing intermittent fasting. Follow the following tips to prevent and avoid nagging pains while enjoying the health benefits.


1. Eat your calories


If you're not fulfilling your body's nutritional needs during fasting, it can do more harm than good. Restriction of calories for a long period of time can even result in malnutrition [14].


Make sure you eat a healthy diet that compliments your fasting regimen, such as fresh fruits, vegetables, meat, and healthy fats. Steer clear of foods high in sugar and empty calories like junk food and soft drinks. You can replace caffeinated beverages with more nutritious alternatives a few days before starting your fasting routine. This is a great way of avoiding caffeine withdrawal headaches during fasting.


Count your calories and make sure you consume the right foods to replenish your body's needs. You can even ask your dietician to create the perfect eating plan during your intermittent fasting.


Keep in mind that a healthy diet will help you reap the full benefits of intermittent fasting!


2. Stay hydrated


Try to hit the mark of drinking 8 glasses of water a day. But, if your fasting regimen doesn't allow you that, include water-rich foods and an electrolyte drink in your diet.


An electrolyte drink, such as Hydrant Mix will not only hydrate you but also fulfill your mineral needs with every sip. It contains magnesium, sodium, zinc, and potassium and refreshing flavors of real fruits to enhance your fasting experience. In addition, hydration will improve your sleep cycle and reduce hunger during fasting [15].


The color of urine is the easiest way to know if you're properly hydrated or not. Ideally, your urine should be pale yellow. In the case of dehydration, you'll notice a darker shade of yellow.



3. Exercise!


Intermittent fasting and a regular workout routine is the ultimate duo to burn down the fat in your body. Not only will exercising burn the calories but also regulate your hormones that are essential to achieving that youthful and lean body!


regular workout routine


4. Choose a customized fasting plan


If you've never followed an intermittent fasting routine before, you will need some time to adjust to the new lifestyle. Be flexible in the beginning! Figure out which type of fasting regime works best for you. It's advised to keep your healthcare provider in the loop to avoid any complications.


Instead of fasting for 16 hours right off the bat, start with 8 hours and work your way up to an advanced level of intermittent fasting [11].


Don't try intermittent fasting without consulting your doctor if you're diabetic, pregnant, or have other medical conditions.



Final Words


Intermittent fasting headaches are nothing to worry about! In most cases, these mild to moderate pains can subside within a week as your body starts to adopt new eating habits.


Fasting headaches can be easily prevented if you give your body all the essential calories it needs. Try a flexible fasting schedule initially; listen to your body and how it responds to your fasting regimen.


However, if the headache persists, there must be an underlying health condition that must be addressed immediately. Contact your healthcare providers and discuss the symptoms.  





[1]     P. Torelli and G. C. Manzoni, "Fasting headache," (in eng), Curr Pain Headache Rep, vol. 14, no. 4, pp. 284-91, Aug 2010.
[2]     (2022). Intermittent Fasting: How It Works and 4 Types Explained. Available:
[3]     K. Gunnars. (2021). 10 Evidence-Based Health Benefits of Intermittent Fasting. Available:
[4]     C. Lawhorn. (2020). Hypoglycemia and Headaches. Available:
[5]     "The International Classification of Headache Disorders, 3rd edition (beta version)," (in eng), Cephalalgia, vol. 33, no. 9, pp. 629-808, Jul 2013.
[6]     M. Khorsandi. (2019). Is hypoglycemia causing your migraines? Available:
[7]     D. J. Mercola. (2017). How Dehydration Affects Your Brain Function. Available:
[8]     Hyponatremia. Available:
[9]     D. L. J. Epstein. Sleep and Mood. Available:
[10]   T. J. Legg. (2018). How to tell if stress is affecting your sleep. Available:
[11]   T. Ryan. (2022). Why Intermittent Fasting Can Lead to Better Sleep. Available:
[12]   D. R. Wilson. (2019). What to know about caffeine withdrawal headaches. Available:
[13]   J. Kubala. (2018). 8 Symptoms of Caffeine Withdrawal. Available:
[14]   M. M. Grajower and B. D. Horne, "Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus," (in eng), Nutrients, vol. 11, no. 4, p. 873, 2019.
[15]   N. J. McKay, I. V. Belous, and J. L. Temple, "Increasing water intake influences hunger and food preference, but does not reliably suppress energy intake in adults," (in eng), Physiol Behav, vol. 194, pp. 15-22, Oct 1 2018.

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