I was at a fitness networking event some time ago and met a woman who, as well as being a personal trainer, was touting the virtues of some particular "cleanse" -- and, it sounded to me, making a good portion of her income, selling it to her clients and anyone else who would listen. "You carry so many pounds of undigested matter in your intestines"... "need to rid the body of toxins".... and so on, and so on...
I recieved emails for months attempting to entice me into trying it and I think I finally blocked her email address because 1) this hard-sell approach to marketing just does not sit well with me and 2) I haven't heard any empirical evidence to support the necessity for "cleansing" or "detoxifying".
I have a very forward-thinking MD (she keeps herself well informed on alternative therapies) and I spoke to her briefly about it and she echoed my feeling that there were no studies to suggest that there was any need for any of these (sometimes expensive) therapies. I also have a client who is a doctor who advised that many of these cleanses simply act as laxatives and posited that Metamucil would work just as well for a fraction of the cost.
I have no doubt that eating a healthy diet that limits things like saturated fats, sugar, alcohol, processed meats; and advocates lots of raw fruits and vegetables will help anyone feel better and aid in weight loss. I also feel that, for most people, the occasional "fast" (choose any one you like--one-day lemon water, all grapefruit for a week, pureed soups for a month) would make one feel lighter (you would definately lose weight though you may also be malnourished) and is probably not harmful... but I don't believe them to be necessary or beneficial in "detoxifying".
And some links that echo my thoughts on this (and yes, you will find a myriad of websites that tout the benefits of various detox cleanses--all with no empirical basis). In the end (no pun intended) it's a personal choice--me? I'll stick with the healthy eating and exercise, thanks.