Taking tempting diet pills? Don't waste your money.

A new Consumer Reports survey shows that people are misinformed about the safety and effectiveness of weight-loss supplements

Published: February 03, 2015 11:00 AM

"Lose weight fast." "Burn more calories, burn more fat." "Designed to help you LOSE 1 1b. a day." "Super Thermogenic." Promises like those on weight-loss supplement packaging make it tempting to pick up a bottle of diet pills. And nearly one in four consumers do, according to a new national survey of nearly 3,000 Americans from the Consumer Reports National Research Center.

"The barrage of advertising leads us to think there's a magic way to melt away 10 pounds—even when we have no evidence that supplements work," says Pieter Cohen, M.D., a physician at Harvard Medical School and the Cambridge Health Alliance who studies supplements.

More than one-quarter of the supplement users in the survey tried the products because they felt they were safe and would help them drop more pounds than other weight loss methods. But unlike prescription and over the counter drugs, supplements don't have to be proved effective and safe before they hit store shelves.

The Food and Drug Administration regulates supplements more like foods, meaning they're generally considered safe unless shown not to be. But our survey revealed that people are confused about how supplements are regulated. About 20 percent of those surveyed believe supplements are tested for safety and effectiveness and that the FDA guarantees that. "The labels on weight loss supplements look like those on over-the-counter medications, and the supplement facts are organized like nutrition facts labels," Cohen says. "There's no way for consumers to tell the difference. It gives you the sense the products are being scrutinized by the FDA."

Not only are people confused about whether supplements are effective, but many are also unaware of their risks. One-quarter of the people in our survey believe the products have fewer side effects than over-the-counter or prescription medications, and nearly 20 percent believe the supplements are safer than prescription drugs because they're "natural." And our survey found that the majority of people who take supplements don't tell their primary care doctors.

"These products can interact with prescription medications, but consumers often feel that supplements are different from prescription drugs, and doctors don't ask about them," Cohen says. More than one-third of the people who used supplements were also taking a prescription medication at the same time for another condition.

Read more about diet pills, such as garcinia cambogia and muscle-building supplements, as well as vitamins, minerals, and other supplements. To lose weight the healthy way, find the best diet for you.

Worse, weight-loss supplements can contain banned drugs. In a recent study, Cohen looked at 27 supplements that had been recalled by the FDA, but were still on the market. Two thirds of those sold for weight loss still contained the banned ingredients. "There's no way to know what's in the bottle," Cohen says. "You're at the mercy of the manufacturer."

Side effects from supplements are common. About half of the people in our survey who used supplements said they experienced at least one side effect, including a rapid heart rate, jitteriness, dry mouth, or digestive problems such as constipation or diarrhea. "Of all dietary supplements, the ones for weight loss seem to cause the most harm—sometimes liver failure and even death," Cohen says.

As for effectiveness, a third of those who took supplements didn't lose any weight. Another third lost some weight. But only nine percent said they lost all the weight they hoped to and kept it off. Chances are, though, the supplement had little to do with it. "If you've spent money on something you think will help, you'll probably pay more attention to what you're eating,"  Cohen says. "Taking the pill acts as a reminder." Indeed, 85 percent of people who said they lost any weight while taking a supplement were also following a diet or exercise program.

The bottom line? We know you've heard it before, but there's no way around diet and exercise. Research shows the key to success is finding a diet you can stick with. We rated 13 popular diet plans in 2013 and found that people lost weight on all of them, although some were judged to be more satisfying than others. A recent review of 48 studies published in the Journal of the American Medical Association found that popular programs like Atkins, Jenny Craig, and Weight Watchers, all worked as well as another. On average, dieters lost about 18 pounds after six months. "It can be tough to stay on these diets," says Bradley Johnston, Ph.D., lead author of the study and assistant professor of clinical epidemiology at the University of Toronto. "But if you get tired of following a low-fat program, for instance, you could switch to a low-carb one, since they're equally effective."

—Deborah Pike Olsen

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