Is it possible for kapalbhati to cure gallstones? How long would it take?

Probably not. Dissolving gallstones has never been successful.They are pretty much there until they are taken out . Not all gallstones need to come out. Only if they cause problems. In fact most people with gallstones don't have any problem with them . When they cause issues it is usually as upper abdominal pain experienced AFTER eating. This problem would need to be evaluated by a general surgeon.