Colon cleansing does not promote weight loss, and it is unnecessary because the body has systems to eliminate toxins.  A colonic may hurt you, especially if colonic irrigation or colonic hydrotherapy is used.  Colon irrigation can upset the fluid balance in the colon to produce cramping, nausea and vomiting.  It can also upset the balance of beneficial bacteria that naturally inhabit the colon.  Furthermore, the equipment can cause a bacterial infection or a deadly perforation of the colon wall.  Excessive colon cleansing can also lead to anemia, heart failure and fluid in the lungs.  To keep the colon clean, drink plenty of water and eat a high fiber diet.  Men need 38 grams of fiber a day and women need 25 grams.