With one-third of Americans obese and many more overweight, the nation is desperate for a weight-loss miracle. But the return of the hCG diet -- a fad popular in the 1970s that combines daily injections of "human chorionic gonadotropin" and extreme caloric restriction -- has some weight-loss experts worried.
"We're so desperate to have good solutions for weight control that a lot of people with good common sense literally suspend it when it they confront weight-loss claims," Dr. David Katz, director of the Yale University Prevention Research Center, said. "This diet is appalling. It takes irresponsible diets to new heights."
HCG is a hormone first produced by the developing embryo and then the placenta during pregnancy to help nourish the womb. Because calories are re-routed from mother to fetus during pregnancy, hCG diet promoters say, injecting the hormone will help curb appetite and allow dieters to get through a day on the energy equivalent of a turkey sandwich.
"A 500-calorie-a-day diet is just plain dangerous," Katz said. "When you restrict calories to that level, there's a real risk for not providing your body with enough essential amino acids, so it scavenges itself. In some instances, it can cause the body to scavenge from critical places, like the heart."
The danger of very low-calorie diets has been well documented since their rise in popularity in the '70s. A 1981 study published in the American Journal of Clinical Nutrition described 17 people, all of whom were initially obese and had significant and rapid weight loss, who died suddenly of ventricular arrhythmia after a median five months of dieting.
The lowest recommended caloric intake per day is 1,200 calories for women and 1,500 for men, according to the National Institutes of Health. Restricting calories beyond those limits should only be done under doctor supervision because of the health risks.
Some milder versions of the hCG diet allow dieters to consumer 800 calories per day, and use hormone creams or drops instead of injections.
"Frankly, it's all variations of the same nonsense," Katz said, calling hCG injections an expensive placebo effect.
More than a dozen clinical trials have failed to support a role for hCG in weight loss. But on a Feb. 21 episode of Fox's "The Dr. Oz Show," Dr. Mehmet Oz himself called for more research into the hormone's hunger-hindering effects.
"By researching hCG ... we might find new ways to help millions of people, who do not have another solution, find an option," he said. "And, for that reason, I think it's worth investigating."
But many experts disagree with Oz's hCG diet endorsement (under doctor supervision, he thinks "it's worth trying it"). In an article posted on the show's website, Harvard Medical School's Dr. Pieter Cohen laid out the facts and fiction surrounding the controversial diet.
"Unfortunately, the injections don't make starving yourself any safer and, in fact, might make it more dangerous," Cohen wrote.
During pregnancy, hCG influences the levels of other hormones, including estrogen and progesterone.
"Although hCG injections could have long-term health effects, the truth is we just don't know," Cohen wrote.
The U.S. Food and Drug Administration calls hCG supplements illegal and fraudulent, and prevents direct-to-consumer sale. But because hCG is approved for other reasons, such as fertility treatments, doctors can prescribe it if they choose.
Stories of hCG diet success are easy to find; no surprise given the dramatic caloric restriction involved. But while the initial results may be motivating, the diet is not very sustainable.
"You might lose weight fast but you'll gain it all back when you go back to living like a normal person, again," Katz said. "And if you do stick with it, you'll be very thin but I doubt you'll be very healthy."
Weight-loss programs that combine more modest calorie reduction and exercise are a better bet for keeping the pounds off, Katz said.
"The hCG diet is not only a silly fad diet," he said, "but it's also a dangerous one."