What are the potential side effects of fasting?

The side effects of fasting occur primarily during the transition phase from eating to consuming nothing. Potential side effects include a spike in uric acid, feeling cold, moodiness, headaches, increased stomach acid, nausea when eating, fainting (if prolonged fasting is done too quickly), and hair loss. However, if you push through the symptoms and start the ketogenic diet and intermittent fasting correctly, they shouldn't be a significant problem.