"It wasn't that hard to pull off, and I'd do it again in a heartbeat," raved London-based fashion stylist Alison Edmond in February's Marie Claire. "In the end, I lost a total of 25 pounds, ending up at a weight I hadn't been in 10 years." Despite success stories like hers, scientific evidence on the plan is shaky at best. In 1995, researchers analyzed 14 clinical trials on the hCG diet. Only two concluded hCG was any more effective than a placebo at helping people lose weight. And nearly 10 years earlier, a report in the Canadian Medical Association Journal stated hCG has "no value" as a means of managing obesity, and that the diet has been "thoroughly discredited and thus rejected by the majority of the medical community."
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Detractors say the hormone isn't some miracle ingredient to weight loss—the restrictive diet is. "If you don't eat, you lose weight," Cohen says. "If hCG truly diminished hunger, it would be a wonderful drug. But if that were the case, why couldn't you just modestly reduce your intake while using it? Why would you have to simultaneously starve yourself?" But believers insist that, thanks to hCG, they can stick to a low-calorie diet without hunger pangs, while losing unwanted fat. They're adamant that hCG is essential to the diet's success. "People are strongly convinced that this hormone will keep them on a 500-calorie diet. And the power of suggestion can be a very strong force," says Cohen.
Of course, the regimen isn't without risks. The hormone is known to cause headaches, blood clots, leg cramps, temporary hair thinning, constipation, and breast tenderness. The FDA has received at least one recent report of an HCG dieter developing a pulmonary embolism, a potentially fatal blood clot in the lung, says agency spokesperson Shelly Burgess. Yet, the hormone's full risk profile is unknown. "HCG was studied briefly [for weight loss] and found to be ineffective, so we have no idea what its potential risks are," Cohen says. "Do I have data that it causes heart attacks, stroke, or cancer? No, I don't, because we just don't know at this point." While hCG may be safe on its own—the FDA says it's safe as an infertility treatment—pairing it with an extremely low-calorie diet could have unexpected side effects.
Two years ago, Lori Hill, 40, of Salt Lake City, Utah, began a 28-day hCG diet cycle. She says she lost about 26 pounds, including thigh fat, largely without hunger. But she felt ill almost immediately, and by the last week of the diet, Hill—a fit and active soccer referee—couldn't climb a flight of stairs without gasping for breath. The effort made her muscles burn and shake, too. After completing the cycle, Hill regained all the weight she had lost, plus an additional 15 pounds. "I starved myself and threw all my nutrients out of whack," she says. "You're tricking your body into letting you starve, without feeling any major hunger. What you're doing to your body just isn't worth it."
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There's no question that 500 calories a day is tantamount to malnutrition—dieters should never dip below 1,200, say experts—and federal dietary guidelines recommend more than three times the amount of calories the diet prescribes for women ages 19 to 30. Moreover, extremely low-calorie diets can cause severe bone and muscle loss, electrolyte imbalances, gallstones, and even death. "I've heard a lot of people say the side effects of this diet are overwhelming," says registered dietitian Keri Gans, a spokesperson for the American Dietetic Association. "And they could start as soon as one day in—you'll start feeling irritated and tired."