In the International Classification of Headache Disorders, fasting headache is classified as headache attributed to disorder of homeostasis.
It means that these headaches are associated with metabolic or systemic disruptions and diseases. While fasting can be one of the causes, you will possibly feel similar symptoms when suffering from a headache caused by high altitude, diving, or sleep apnea.
How does a headache while fasting feel? It is likely to be diffused or located in the frontal region, and the pain is non-pulsating and of mild or moderate intensity. However, depending on the headache cause and many other factors, it might feel differently.
The likelihood of developing a fasting headache increases directly depending on the duration of the fast. In most cases, the headache occurs after around 16 hours of fasting and resolves within 72 hours after resuming food intake. Therefore, people doing prolonged fasting, are more likely to experience a headache.
Any other factors that can increase the probability of suffering from a headache during fasting? While much remains to be understood about this, studies show that headache sufferers have a higher risk of developing a headache during fasting than people who do not usually suffer from headaches.
While the precise cause of fasting headache is still being discussed, there are a few factors that could be responsible for this annoying fasting side effect. Dehydration, caffeine withdrawal and hypoglycemia, or in other words, a fall in blood sugar to levels below normal, could be the three most common fasting headache causes.
Still, it’s important to also pay attention to lesser-known headache triggers like stress, fatigue and lack of sleep during the fast. Especially at the beginning of your intermittent fasting journey, your body is undergoing drastic lifestyle changes that can cause emotional and physical discomfort.
Now when we have identified some of the possible fasting headache causes, let’s get to the most important part – figuring out how to cure it and have pain-free fasting hours.