I get headaches when I fast. What can I do? As above, try increasing your salt intake. Headaches are quite common the first few times you try a fast. It is believed that they’re caused by the transition from a relatively high-salt diet to very low salt intake on fasting days. Headaches are usually temporary, and as you become accustomed to fasting, this problem often resolves itself. In the meantime, take some extra salt in the form of broth or mineral water.

