There's a lot less of Margo today. She lost more than 100 pounds. The key to Margo's success was not rigorous diet or exercise. She had the help of the herbal supplement ephedra. That is the active ingredient, along with caffeine, in dozens of so-called natural weight-loss products.
Pharmacologist Neal Benowitz says ephedra is no miracle pill. "It causes your heart rate to go up, it causes your blood pressure to go up. It's like amphetamine, not quite as potent, but similar," he says.
Increasing a person's metabolism makes these products work, but it may also make them deadly. Dr. Benowitz looked at 140 adverse reactions reported to the U.S. Food and Drug Administration over a two-year period. He concluded that two-thirds of the medical problems reported were likely caused by supplements containing ephedra.
"There is a precedent for stimulant drugs to cause people to die suddenly, especially when you're exercising." says Benowitz.
And any underlying cardiac problem can add to the risk.
On Oct. 1, 1998, Ann Marie Capati was working out at a gym when she suffered a fatal stroke.
On the advice of a trainer at the gym, she had started taking supplements, including Thermadrene which at the time included the active ingredients ephedra and caffeine.
Her husband Doug Hanson believes that, for Ann, exercise and ephedra was a lethal combination. "She had high blood pressure, which she had during the first pregnancy with our daughter and in some women it goes away after the pregnancy's finished," explains Doug. "In other women, it carries on. It was mild high blood pressure."
He filed lawsuits against several supplement makers, Ann's gym and her trainer who he says should have known that high blood pressure put her at high risk.
Pathologist Steven Karch is an expert on stimulant-related death. He believes critics are exaggerating ephedra's risks. "If you consider the 12 million people who took it last year, your odds are pretty small," he says. "I think people with no medical problems and no issues who need to lose weight are OK."
But even Dr. Karch, who speaks on behalf of the supplement industry, says some people should not take it: "Ephedra's not for everybody. I mean, pregnant women shouldn't ever remotely think about it, and neither should anybody who knows they have high blood pressure or a heart attack in the past or anything."
Dr. Benowitz urges caution. "If you're a young, healthy person and you take a dietary supplement to help you lose weight and you drop dead, that's a pretty serious event, even if it's rare," he says. "And the question is, are you willing to take that chance?"