There's a good article about the colon cleansing fad in today's Wall Street Journal;

Does your colon really need cleansing?

According to a profusion of Web sites, clinics and wellness spas, the typical American diet of processed foods, pharmaceuticals, stress and lack of exercise is clogging up our lower intestinal tracts, leaving them inflamed and lined with waste—and leaking toxins into the body that cause problems ranging from headaches and chronic fatigue to arthritis and cellulite. All that "stubborn fecal matter" also contributes to bulging bellies and expanding waistlines, cleansing proponents claim.

Read the rest at Does Your Colon Really Need Cleaning?