Animals DO NOT fast on a schedule. Yes, annually, some animals fast, and yes, when in pain or ill they fast. Arbitrary fasts, such as every week, fortnight, or month? No, never. More energy? I eat for fuel and sleep for energy. My intention is keeping health practices simple and easy. I know, from a relatively newbie perspective, fasting regularly might make sense. What makes the most sense to me is living my life in such a healthful fashion that fasting is never required, unless I'm in great pain, or ill, or in some other way feel far from my usual healthy self. Does this help?