The hCG diet — one of the most controversial weight-loss plans ever — is once again playing in a doctor's office near you. And it's causing a stir, as well.

The diet combines daily shots of the pregnancy hormone human chorionic gonadotropin (hCG) with a 500-calorie-a-day diet that has its fans ecstatic about weight loss of as much as a pound a day.

But to prove there's no slam-dunk when it comes to dieting, skeptics are equally adamant that the diet is ill conceived and ineffective. At best, they say, anybody would lose weight on a 500-calorie diet — which, they add, is very unhealthy.

At worst, they note, there are health risks from using the hCG and the restricted food intake.

Making the clash more interesting, Dr. Mehmet Oz, the in-house medical guest on Oprah's popular TV show, said on the Feb. 21 episode he thinks the diet has some promise and at least deserves to be studied.

In turn, Harvard's Cohen posted his own vehement and opposite take.

He starts with a true-false quiz about hCG that finds you can, in fact, lose 30 pounds in one month. Some dieters do swear buy it. Doctors say it doesn't work. And the FDA calls hCG supplements illegal and fraudulent. That's all true. But there's more to know about it, he says.

A U.S. News article on Tuesday reported on the popularity of the hCG injections and what it calls a "near starvation diet" and notes significant concerns — and some pretty ardent advocates.

It's not a cheap diet, it says, costing (mostly) women hundreds or more a month for a doctor consultation, supply of the hormone, syringes and training in how to do the injection, but there is little evidence that the regimen is effective, it says.

Many patients are told that the hCG will induce their bodies to eliminate fat from areas such as the upper arms, bellies and thighs. They're also told the hormone will prevent them from feeling hungry or tired despite their low calorie intake.

Cohen told The Times that the diet is used for "manipulating people to give them the sense that they're receiving something that's powerful and potent and effective, and in fact, they're receiving something that's nothing better than a placebo."

The U.S. Food and Drug Administration has approved hCG injections as a treatment for infertility and other uses. It's legal to prescribe it for use "off label" for weight loss, but its packaging must state that it has not been shown to increase weight loss, doesn't not distribute fat in a more "attractive" way and does not "decrease hunger and discomfort" from a low-calorie diet that has in its entire 500-calorie day been likened to having a single turkey sandwich with condiments and trimmings.

FDA spokesman Christopher Kelly also told the New York Times that hCG injection carries risks of blood clots, depression, headaches and breast tenderness or enlargement.

The New York Times article traces the history back to a diet popularized in the '50s by A.T.W. Simeons, a Roman doctor who said he used it on more than 500 patients, publishing his results that year in The Lancet, Britain's medical journal. In 1995, a Dutch study revisited the diet, analyzing 14 randomized clinical trials of the diet. Only two saw any improvement on the diet compared to the same 500-calorie diet and placebo saline injection.

But doctors who prescribe it say they have seen it work, regardless of what the research shows.

Diets of all sorts have been embraced and lampooned over the years. has not only an explanation of how the hCG diet works, but also a look back at some memorable "diet fads, crazes and schemes."

It notes that "in the 1920s, overweight consumers were sold 'reducing soap,' the ads for which promised to eliminate fat on any part of the body that was washed with this miracle soap. From the 1920s through the 1950s, some people would partake of the tapeworm diet, which didn't require much change in diet, other than consuming a tapeworm." The 1950s brought in the vibrating belt developed by a Swedish doctor to shake loose the excess pounds.