Dr. Joe Schwarcz is warning the public about the latest diet fad that requires injections of a hormone.

The hormone HCG is produced by the placenta, and is used in fertility treatments, but it has never been approved for weight loss.

It was first dreamed up as a weight-loss program in the 1950s when a british endocrinologist tried it.

"He injected patients with it and he said if you put them on a very low-calorie diet, they can sustain the diet with HCG," said Dr. Schwarcz.

However that low-calorie diet was just 500 calories -- about 1/4 what an adult male needs every day.

"It was an absurdity and it disappeared for 30-40 years until Kevin Trudeau resurrected it," said Dr. Schwarcz.

For the full reasons as to why people should not try this dangerous 'diet', watch the video.