Why do you get a headache when fasting?

Dehydration: Fasting can lead to dehydration, which can cause headaches. When you don't drink enough fluids, your body doesn't have enough water to function properly and this can lead to a headache.

Electrolyte imbalance: Fasting can also cause an imbalance in your electrolytes, such as sodium, potassium, and magnesium. This imbalance can also lead to headaches.

Withdrawal from caffeine or sugar: If you're used to consuming caffeine or sugar on a regular basis, suddenly stopping can lead to withdrawal symptoms, including headaches.

Stress: Fasting can also be stressful for your body, and stress can trigger headaches.

It's important to note that not everyone who fasts will experience headaches. However, if you do get a headache while fasting, it's important to stay hydrated and to eat a healthy diet. You may also want to try taking over-the-counter pain medication, such as ibuprofen or acetaminophen. If your headache is severe or persistent, it's important to see a doctor.