Fasting headaches are linked to low blood sugar (hypoglycemia) and dehydration.
They can also be associated with caffeine withdrawal.
The headache usually goes away after eating.
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The headache pain is typically mild to moderate in intensity.
Still, fasting can induce a migraine in people who have migraine headaches.
Not eating may cause a fasting headache or it can be a trigger for a migraine.
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The longer you go without eating, the more likely it is that a fasting headache will occur.
Causes
The exact cause of fasting headaches is still not known.
There are a few theories for why this happens.
Hypoglycemia
One possible cause for fasting headaches ishypoglycemia, or low blood sugar.
This leads to a fasting headache.
This, like the blood sugar link, is controversial too.
A caffeine-withdrawal headache usually occurs about 18 hours after the last caffeine intake.
This is similar to the pattern seen in a fasting headache.
In addition, a caffeine-related headache has symptoms similar to a migraine and a fasting headache.
However, people still get fasting headaches even when they don’t regularly consume caffeine.
This suggests that caffeine withdrawal isn’t a primary cause of fasting headaches.
In fact, many scientists think that a caffeine withdrawal headache is a separate entity from a fasting headache.
Indeed, these headaches are coded separately in the system that medical researchers use to classify headaches.
Dehydration or Stress
Other causes of fasting headaches have been proposed too.
Sometimes, stress is what causes people not to eat in the first place.
The bottom line here is that the precise cause of fasting headaches is still unknown.
There may be a number of factors involved.
It also may vary for each individual.
There are several different intermittent fasting protocols.
They usually resolve once you start eating again.
If you do experience a headache during intermittent fasting, it may help to increase your water intake.
Prevention
The obvious way to prevent fasting headaches is to not skip meals.
This may be all your body needs to ward off a headache.
Some people fast for religious reasons.
This often means going a much longer time without food and water.
Religious fasts may not allow for eating or drinking even small amounts for ward off a headache.
Headaches during religious fasts may be related to hypoglycemia or to dehydration and caffeine withdrawal.
see to it you are also well-hydrated before beginning a period of abstaining from water and other liquids.
However, these are best avoided on an empty stomach.
Summary
A fasting headache can feel like a tension headache.
Scientists still don’t know the exact reason why not eating can cause a headache.
It does seem to happen more in people who get headaches routinely.
Get our printable guide for your next doctor’s appointment to help you ask the right questions.
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