Weighing The Health Risks, In Your Body

In this overweight nation, there's a feeding frenzy for weight-loss pills. Metabolife International says it expects to sell $900 million worth of supplements this year. At its peak, Fen-Phen was taken by millions of Americans eager for a quick way to shed extra pounds. More than 1 million have tried the drug Meridia since its debut in 1998. And earlier this year, after just one month on the market, close to 100,000 prescriptions had been written for a competitor pill, Xenical.

But the wish for an effective, risk-free diet pill is about as realistic as the search for a free lunch. Both Xenical and Meridia (like Fen-Phen) are prescription diet drugs approved by the Food and Drug Administration. Metabolife, by contrast, is a "dietary supplement." The FDA considers it a food, not a drug, so it doesn't require government approval before landing in stores. The supplement contains a smattering of herbal components, including bee pollen, ginger and goldenseal. Its most active--and controversial--ingredients are two stimulants: 40 milligrams of caffeine (about what you get in a shot of espresso) and 12 milligrams of ephedra, which is derived from a Chinese herb called mahuang. The company says the compound works by raising the body's metabolic rate, inducing a person to burn more fat. They say it also increases energy levels--making dieters more active--and suppresses appetite.

The scientific data on Metabolife's efficacy and safety, however, is limited. Two unpublished studies indicate that the compound does have some effect on the body. Researchers at Vanderbilt University found that the metabolic rates of 17 moderately obese patients increased slightly (between 3 percent to 6 percent) when they took Metabolife compared with a placebo. The study was preliminary and says nothing about whether or not the supplement actually aids in weight loss. In another experiment involving 60 patients at Columbia University and New York's St. Luke's-Roosevelt Hospital, doctors reported that patients who took Metabolife for eight weeks lost more weight than patients taking a placebo. But the study was too short, says a member of the research team, to conclude with any certainty that Metabolife is safe in the long term. Some patients reported side effects such as jitteriness, nervousness and insomnia while taking the substance.

Metabolife's Michael Ellis says that his product works and is "absolutely safe" when used properly. But some experts worry about ephedra, which can constrict the blood vessels while speeding the heart and nervous system. Anecdotal reports submitted to the FDA have linked various products containing ephedra with seizures, strokes, heart attacks and even death. FDA officials proposed regulations that, among other things, would limit the amount of ephedra in supplements like Metabolife to 8mg per pill. But in July, the General Accounting Office concluded that there was not enough solid evidence to support such stringent limits. For now, it is up to consumers and their doctors to weigh Metabolife's reported benefits against its possible risks.

Prescription diet pills have their own risks. Fen-Phen was pulled off the market in 1997 after researchers linked it to heart-valve damage. And though Meridia and Xenical have not been associated with such severe reactions, they do have documented side effects. Meridia, which acts on brain chemicals to reduce appetite, can cause a spike in blood pressure in some patients. And because Xenical decreases absorption of dietary fat, it can provoke major intestinal upset. The best prescription, in the end, may be caution and a healthy dose of common sense.

Ephedra combined with caffeine--the active ingredients in Metabolife--can have powerful effects on the body:

Nervous System: Can curb appetite and increase alertness and energy level. Problems may include nervousness, jitteriness and insomnia.

Cardiovascular: Can raise blood pressure and increase pulse rate. Some users experience heart palpitations.