Fasting is one of those things that gets recommended everywhere, particularly amongst Buddhist writers. My experience of it is confined to pre-ops and preps, and includes automatic hunger migraine. Thus I assumed that it, like seated meditation, is something my body flatly forbids. But fasting when you have no appetite-- when, indeed, your innards double-dog-dare you to put anything inside them, including water-- turns out to be a doddle. Only now does it occur to me that the dragging tiredness might be partly due to hunger and not the stomach flu which ('ware TMI) lost me six pounds between yesterday morning and today.
Fasting also may have allowed me to meet my work commitments today, but oh! am I glad my work commitments are over and I have all tomorrow to sleep.