IMHO amount of sessions really depends on your age and history of constipation and bowel movements... and 1 session is definately not enough because the colon is several feet long in distance... If your colon has a lot of old and dried up compacted poop in it which may be likely given your long history of constipation it is very unlikely that 1 colonic will clean you out... dare I say impossible! It is highly unlikely that the water is going to get into the whole length of your colon in one session. 12 sessions cleaned me out after years of constipation. I am in my 40's. Good luck!