I fast regularly. I am also compete regularly in powerlifting and olympic weightlifting competitions. my fasts are total water-only fasts: zero calorie. I co

I fast regularly. I am also compete regularly in powerlifting and olympic weightlifting competitions. my fasts are total water-only fasts: zero calorie. I continue my normal workout habits (lifting weights, obviously, and the usual run/swim/dance/other-sort-of-cardio) but tone it done a bit, depending on the length of the fast. If I am doing a 3 day fast things barely change. If I am fasting for 5+ days my workouts that week proceed but I take a "deload" week. I take the next week following the fast a bit easier, and by the 2nd week I am lifting the same weights as pre-fast. I don't know a lot about human metabolism or biology, but in my experience my muscles don't suddenly disappear after missing a meal. To repeat - I can fast for up to 3 days without messing up my training.