Can you safely fast-track weight loss?

Fat Burners: “Rev up your metabolic rate to ‘burn’ stored fat!”

We’ve all seen the claims that fat burners—which usually include some sort of stimulant—raise your metabolic rate so you burn fat faster. But when you stoke metabolism you also risk straining the heart—a lesson we learned in 2003 when studies found that ephedra, one of the most popular fat burners, has dangerous side effects including heart attacks, strokes and even death. The Food and Drug Administration subsequently prohibited its sale.

Today’s fat burners usually contain milder stimulants. One, Citrus aurantium (bitter orange), is touted as a safer alternative to ephedra, but a recent review by researchers at Johns Hopkins School of Medicine concluded that more and larger studies are needed to determine the herb’s effectiveness and safety. Caffeine, another common addition to fat-burner formulas, boosts metabolism only minimally. In a 2007 study, 50 mg of caffeine (the amount in 1⁄2 cup of coffee) increased subjects’ calorie-burning rate by about 6 percent. That comes to about 17 extra calories burned off during the four hours the subjects were tracked. But those ­results may be misleading, since the subjects’ usual intake of coffee was low. As any Starbucks regular can tell you, people with a regular caffeine habit are less stimulated by caffeine.

Fucoxanthin, a compound found in brown seaweed, is reported to act differently from the stimulant-type fat burners, although its precise mechanism is still unclear. Animal research from Hokkaido University, Japan, found that abdominal fat was slightly reduced in rodents after they were fed fucoxanthin. Although this sounds promising, it’s too early to tell if humans will benefit too.

Next: Appetite Suppressants, do they work? »

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