What are weight-loss dietary supplements and what do they do?
The proven ways to lose weight are eating healthful foods, cutting calories, and being physically active. But making these lifestyle changes isn’t easy, so you might wonder if taking a dietary supplement that’s promoted for weight loss might help.
This fact sheet describes what’s known about the safety and effectiveness of many ingredients that are commonly used in weight-loss dietary supplements. Sellers of these supplements might claim that their products help you lose weight by blocking the absorption of fat or carbohydrates, curbing your appetite, or speeding up your metabolism. But there’s little scientific evidence that weight-loss supplements work. Many are expensive, some can interact or interfere with medications, and a few might be harmful.
If you’re thinking about taking a dietary supplement to lose weight, talk with your healthcare provider. This is especially important if you have high blood pressure, diabetes, heart disease, liver disease, or other medical conditions.
What are the ingredients in weight-loss dietary supplements?
Weight-loss supplements contain many ingredients—like herbs, fiber, and minerals—in different amounts and in many combinations. Sold in forms such as capsules, tablets, liquids, and powders, some products have dozens of ingredients.
Common ingredients in weight-loss supplements are described below in alphabetical order. You’ll learn what’s known about whether each ingredient works and is safe. Figuring out whether these ingredients really help you lose weight safely is complicated, though. Most products contain more than one ingredient, and ingredients can work differently when they’re mixed together.
You might be surprised to learn that makers of weight-loss supplements rarely carry out studies in people to find out whether their product works and is safe. And when studies are done, they usually involve only small numbers of people who take the supplement for just a few weeks or months. To know whether a weight-loss supplement can help people lose weight safely and keep it off, larger groups of people need to be studied for a longer time.
Ephedra, an ingredient banned from dietary supplements
Ephedra (also called má huáng) is a plant containing substances that can stimulate your nervous system, increase the amount of energy you burn, increase weight loss, and suppress your appetite. In the 1990s, ephedra was a popular ingredient in dietary supplements sold for weight loss and to enhance athletic performance. In 2004, the U.S. Food and Drug Administration (FDA) banned ephedra in dietary supplements, concluding that it isn’t safe. Ephedra can cause nausea, vomiting, anxiety, mood changes, high blood pressure, abnormal heartbeat, stroke, seizures, heart attack, and death.
How are weight-loss dietary supplements regulated?
The FDA is the federal agency that oversees dietary supplements in the United States. Unlike over-the-counter and prescription drugs—which must be approved by the FDA before they can be sold—dietary supplements don’t require review or approval by the FDA before they are put on the market. Also, manufacturers don’t have to provide evidence to the FDA that their products are safe or effective before selling these products.
When the FDA finds an unsafe dietary supplement, it can remove the supplement from the market or ask the supplement maker to recall it. The FDA and the Federal Trade Commission can also take enforcement action against companies that make false weight-loss claims about their supplements; add pharmaceutical drugs to their supplements; or claim that their supplements can diagnose, treat, cure, or prevent a disease.
For more information about dietary supplement regulations, see the Office of Dietary Supplements publication, Dietary Supplements: What You Need to Know.
Can weight-loss dietary supplements be harmful?
Weight-loss supplements, like all dietary supplements, can have harmful side effects and might interact with prescription and over-the-counter medications. Many weight-loss supplements have ingredients that haven’t been tested in combination with one another, and their combined effects are unknown.
Tell your healthcare providers about any weight-loss supplements or other supplements you take. This information will help them work with you to prevent supplement-drug interactions, harmful side effects, and other risks.
Fraudulent and adulterated products
Be very cautious when you see weight-loss supplements with tempting claims, such as “magic diet pill,” “melt away fat,” and “lose weight without diet or exercise.” If the claim sounds too good to be true, it probably is. These products might not help you lose weight—and they could be dangerous.
Weight-loss products marketed as dietary supplements are sometimes adulterated with prescription drugs or controlled substances. These ingredients won’t be listed on the product label, and they could harm you. The FDA puts out public notifications about tainted weight-loss productsexternal link disclaimer.
Interactions with medications
Like most dietary supplements, some weight-loss supplements can interact or interfere with other medicines or supplements you take. If you take dietary supplements and medications on a regular basis, be sure to talk about this with your healthcare provider.
Choosing a sensible approach to weight loss
Weight-loss supplements can be expensive, and they might not work. The best way to lose weight and keep it off is to follow a healthy eating plan, reduce calories, and exercise regularly under the guidance of your healthcare provider.
As a bonus, lifestyle changes that help you lose weight might also improve your mood and energy level and lower your risk of heart disease, diabetes, and some types of cancer.