Last Updated on November 9, 2023 by Fasting Planet
Ugh, your head hurts. Then again, you’ve been fasting for quite a while now, maybe something like seven or eight hours? You’ve almost lost track. Is it usual to experience a headache or several while fasting or should you maybe call your doctor?
Fasting can lead to both headaches and migraines. These can be caused by the stress of such a big dietary change, dehydration, caffeine withdrawal, and/or hypoglycemia.
Ahead, we’ll discuss more about why fasting gives you a headache, how long the headache may last, and what you can do to put a stop to it. Let’s start.
Can Fasting Lead to Headaches? How?
Have you ever overslept on a workday, rushed through your morning routine, forgot to eat breakfast, and then felt your head begin to ache a few hours after you arrive at the office? There are several factors at play in such a scenario that also occur when you’re fasting.
Let’s explore those factors that cause fasting headaches now.
Stress
When you go on an intermittent fast, you’re doing so for a variety of health benefits. You could have weight loss, promote better immune health through autophagy, give your digestive system a break, and maybe live longer. Yet if this is your first or second fast, your body still has no idea why you’re suddenly not eating.
The internal stress combined with the external stressors that fasting can induce (hunger and crankiness being two of them) can cause that achy head you’ve been dealing with for hours at a time. Stressheadaches, also referred to as tension headaches, can affect the muscles in the scalp and neck specifically.
Dehydration
Uh-oh, are you not drinking enough water? Even in a fasted state, it’s still important that you maintain your water consumption throughout the time and day. This can provide a temporary feeling of fullness, plus, it’s very much necessary you stay hydrated. You’re losing about 20 percent of your daily hydration by skipping food, so you need to make up for that somehow.
Otherwise, your head will begin aching something fierce. Besides that, you may experience these symptoms:
- Faster heart rate
- Decrease in blood pressure
- Reduced skin elasticity
- Sticky and dry mouth
- Exhaustion
- Dizziness
- Confusion
- Urine that’s a darker color than normal as well as a lower frequency of urine
- Feeling far thirstier than normal
Since dehydration can be fatal if it persists for long enough, make sure you get some water to drink ASAP.
Caffeine Withdrawal
Are you a caffeine lover who can’t start any morning without a hot cup o’ joe? Suddenly quitting caffeinated coffee because of fasting can also trigger a headache. This 2004 press release from Johns Hopkins mentions that caffeine withdrawal is officially a disorder. It’s characterized by these symptoms:
- Muscle stiffness and/or pain
- Vomiting
- Nausea
- Flu-like symptoms
- Concentration issues
- Irritability and depression
- Dysmorphic mood changes
- Fatigue
- Headache
We’d recommend contacting your primary care doctor if you think you’re going through this withdrawal.
Hypoglycemia
Another cause of fasting headaches is hypoglycemia.
What you eat and when contributes to your blood sugar levels. In healthy, non-diabetic patients, your blood sugar will spike when you have a meal and then drop as your body processes and begins digesting that food. Then, gradually, your blood sugar will come down.
If you go long enough without food, such as during intermittent fasting, your blood sugar could drop below recommended levels. This low blood sugar is known as hypoglycemia.
Besides a headache with low blood sugar, you may experience such symptoms as:
- Irritability
- Hunger
- Sweating
- Anxiety
- Shakes
- Pale skin
- Exhaustion
- Changes in heart rate, usually an increase
That said, not all medical experts necessarily agree that hypoglycemia is a culprit of intermittent fasting headaches. After all, your liver can hold onto excess glycogen for days when you’re not eating. Theoretically, that should prevent your blood pressure from plummeting to a low blood sugar enough to develop hypoglycemia.
That said, headaches when hungry can also be contributing to your pain. You may find you get a headache after eating post-fast, which can happen. Headaches after eating should abate as you eat more regularly
Do Fasting Headaches Go Away? How Long Do Intermittent Fasting Headaches Last?
You don’t really care what it is that’s caused your fasting headache. You just want it to go away. Will your fasting headache disappear on its own?
Yes, it can, but typically, you have to resume the consumption of food and/or beverages for this to happen; especially if you get a headache when hungry. Thus, your intermittent fasting headache could last for the entirety of your fast. If that’s 24 hours, then your head may ache and throb for that long. If your fast is two days, then you could be in for a painful 48 hours.
Are Headaches Normal When Fasting?
A headache is usually a sign that you’re not caring for your body, so when you get one, you worry a bit. Should you see your doctor for a fasting headache? Are these abnormal or a completely regular one?
Fasting headaches, while not pleasant, are considered a normal side effect of fasting. Not every faster will get fasting headaches though. Also, as you intermittent fast more often, you may find that your headache disappears depending on what’s causing it.
After all, if it’s dehydration, you’ll learn how to stay hydrated when fasting the more you do it. Caffeine withdrawal may lessen as your body goes longer without caffeine, and the stress that fasting induces will also vanish as your body soon learns what you’re doing and why.
The only cause of fasting headaches that isn’t immediately resolvable like this is hypoglycemia. That said, you can always go on an intermittent fast where you can eat at least once a day, such as the 16:8 fast, the 5:2 fast, or the OMAD diet. That should ward off hypoglycemic symptoms.
What Helps a Headache When Fasting?
If your head is killing you and making it hard to get anything done, try the following methods for alleviating headaches.
Drink Water
Even if the source of your headache isn’t attributable to being under-hydrated, drinking water is still always a good idea. This WebMD FAQs on migraines and headaches mentions that when migraine sufferers in a study consumed 1.5 more liters of water each day, their headaches were not only less painful, but they happened less often too.
Use Heat or Cold
Another option you have is to use heat or cold treatments like a hot compress, heating pad, or a cold pack. With a cold pack, you want to put it directly on your forehead, keep it there for about 15 minutes, stop for 15 minutes, then resume as needed until your headache abates.
Hot treatments like compresses or pads can help and work best at the back of your head or your neck for tension headaches and your forehead for every other type of headache. You can also treat yourself to a steamy shower.
Take Aspirin
Your last option for help is to take an over-the-counter NSAID like aspirin for the pain.
This 2018 report on aspirin resistance in Ramadan fasters as published in PLOS ONE mentions that the resistance of the medication did not change through fasting. However, these patients all also had type 2 diabetes, so that may affect results.
Aspirin should not break your fast since it doesn’t contain calories. If you can eat on your intermittent fast, it’s always better to take aspirin with food than on an empty stomach.
Conclusion
Intermittent fasting can cause headaches from dehydration, caffeine withdrawal, and hypoglycemia. Now that you know more about fasting headaches, you can work harder to manage yours. Best of luck!