Gwyneth loves them. Health spas laud them. But the truth is, colon cleanses and colonics (the process of irrigating your colon with water to release toxins) can have dangerous health consequences. And according to a new study, they may not even work in the first place!The study, conducted by Georgetown University, reviewed published medical literature about colonics from the past decade. The findings: There was little evidence that colon cleansing has any real health benefits, but the laundry list of nasty side effects came in loud and clear.Some of the front-runners? Cramping, bloating, nausea, vomiting, electrolyte imbalance, and even kidney and renal failure. And just when it can’t seem to get worse—even death in extreme cases.MORE: Guide to Alternative Therapies (that Work!)The researchers add that some of the health “spas” that offer colon cleansing are (potentially) staffed with inadequately trained technicians. Some are unlicensed entirely, while others are stamped by organizations like National Board for Colon Hydrotherapy, where technicians are required to have little more than a high school diploma.It’s sad news for those seeking a way to detox or jumpstart a miracle weight-loss cure—those paint-on skinny jeans can be pretty daunting, after all—but it’s more important to stick to remedies that are proven to be both effective and safe for your body.As YouBeauty founder Dr. Michael Roizen puts it: “You’ll produce a lot of waste after a colonic, but the main waste here is of money. Your colon only absorbs water, so there’s no weight-loss benefit from colonics. In fact, you can get the same colon-cleansing and toxin-eliminating effect with a twenty-four hour fast, coffee and water.”In that case, one venti dark roast, please. Hold the mind-numbing cramps and kidney failure.