Anecdotally, I usually feel dramatically better when I fast. There is an incredible mental clarity and productivity that itself makes fasting worth it. I don't

Anecdotally, I usually feel dramatically better when I fast. There is an incredible mental clarity and productivity that itself makes fasting worth it. I don't feel tired when I fast - in fact, I often feel like I could easily go for a 10-mile run. FWIW, it takes getting used to. If you drop everything and do a 24-hour fast after years of "6 meals a day", you will feel cold, irritable, and unproductive. Also, coffee is a powerful thing.