Thousands of people are latching onto a diet that promises rapid weight loss—up to 30 pounds a month—and, judging by its recent surge in popularity, actually delivers. But the so-called hCG diet is either a weight-loss miracle or a dangerous fraud, depending on who’s talking. The plan combines drops or injections of hCG, a pregnancy hormone, with just 500 calories a day. While some believers are so convinced of its power they’ll willingly stick themselves with a syringe, the government and mainstream medical community say it’s a scam that carries too many health risks and doesn’t lead to long-term weight loss.