Although some have fasted from food for 40 (or in rare cases more) days, it's inadvisable go more than 3 days without pipe smoking. Some of us have gone a little longer without a pipe -- but that's informational only, not a recommendation. If you were going to try it, do it under medical supervision. Nobody here wants to say that it's ok, and then you go and have a medical emergency. You can't put that on people. So we're just going to insist on saying: Consult with your doctor. If it works for you, careful not to share your experience with others in a way that encourages them to try it without their own medical supervision.