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Unlike over-the-counter and prescription drugs that have to undergo approval by the Food and Drug Administration (FDA) before they are sold, weight-loss dietary supplements do not require premarket review or approval by the FDA. Manufacturers are responsible for making sure that their supplements are safe and that the label claims are truthful and not misleading, but they don’t have to provide that evidence to the FDA before they sell their products.
2. What about hoodia? It was big a few years ago, but I haven’t heard much about it lately.
Hoodia (Hoodia gordonii) is a cactus-like plant that grows in southern Africa where it has traditionally been used as an appetite suppressant. Even though hoodia products became very popular in the United States several years ago, scientists actually know very little about this ingredient. Only one clinical trial on hoodia has been conducted, and it found that, compared with a placebo, hoodia did not affect the amount of calories people ate or their body weight.
Also, in the past, analyses showed that some hoodia supplements contained very little hoodia or none at all. It’s not known if this is still a problem for hoodia supplements sold today.
3. I drink coffee but try to avoid getting too much caffeine. If a dietary supplement has caffeine, will it be listed on the product label?
Not always. Sometimes it’s hard to tell if a dietary supplement has caffeine and, if it does, how much. Several herbs, including guarana, kola nut, and yerbe mate (or maté), naturally contain caffeine. Green tea and green coffee beans also have caffeine. Product labels will list the ingredients contained in the supplement, but if an herbal ingredient is a natural source of caffeine, the amount is not always mentioned. According to the FDA, it’s safe for most adults to get up to about 400 mg of caffeine (about 4–5 cups of coffee) in a day. More than that can cause nausea, vomiting, rapid heartbeat, and seizures.
Many weight-loss dietary supplements contain other stimulants, such as bitter orange or synephrine. Combining these with sources of caffeine can multiply the side effects.
4. Even if weight-loss dietary supplements won’t necessarily help me lose weight, is there any harm in trying them?
Yes, there could be. Most weight-loss dietary supplements don’t have major safety concerns when used as directed, but some might. Beware of messages like “lose weight without diet or exercise,” “magic diet pill,” and “melt your fat away.” At best, products with claims like these do not live up to them, and even worse, they could be dangerous.
Many weight-loss dietary supplements contain caffeine and other stimulants that can cause problems at high doses. Others could interact with certain medications like warfarin and diabetes drugs. Occasionally, weight-loss supplements are tainted with prescription drug ingredients or controlled substances, making them unapproved—and unsafe—drugs.
Before you try weight-loss dietary supplements, talk to your health care provider to understand what is known—and not known—about these products. This is especially important if you have high blood pressure, diabetes, heart disease, or other medical conditions.
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