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.

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.

Common ingredients in weight-loss dietary supplements

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.

What is berberine?

Berberine is a substance found in a variety of plants, including goldenseal, barberry, Oregon grape, and others. Plants containing berberine have a long history of use in both Ayurvedic and Chinese medicine. In modern times, plants containing berberine have been used for infections, skin diseases, digestive disorders, and other conditions. Berberine is currently being studied for its effects on diabetes and risk factors for heart disease. Recently, it has become popular as a potential weight loss aid.

Will taking berberine help me lose weight?

Some studies suggest that it might, but the evidence is not conclusive.

A 2022 review of 18 studies that examined the effect of berberine on body weight and 23 that examined its effect on body mass index (BMI; a value based on weight and height that may help determine whether a person has a healthy weight) found significant decreases in both weight and BMI in people who took berberine. Effects on weight were seen primarily in people who took berberine in doses of more than 1 gram per day and for more than 8 weeks. Many of the studies included in this review had a high risk of bias, and the outcomes of individual studies were inconsistent. Therefore, additional, high-quality research would be needed to allow definite conclusions to be reached about whether berberine reduces weight and BMI.

Assessing the effects of berberine is also difficult because the amounts and formulations of berberine used in different studies have varied widely, and most of the study participants had health problems, such as diabetes or fatty liver disease, that might have influenced the results. In addition, most studies that looked at the effects of berberine on weight and cardiovascular risk factors were conducted in Asian countries; very few were done in North America.

Is it safe to take berberine?

Some side effects of berberine have been reported in research studies, primarily gastrointestinal symptoms such as nausea, abdominal pain, bloating, constipation, or diarrhea.

Berberine may interact with medicines. For example, it has been shown to interact with cyclosporine, a drug used to prevent rejection of transplanted organs. If you take medicine, talk with your health care provider if you are considering taking berberine supplements.

Exposure to berberine has been linked to a harmful buildup of bilirubin in infants, which can cause brain damage. Therefore, berberine is likely to be unsafe for infants and may also be unsafe for use during pregnancy or while breastfeeding because of possible effects on the fetus or infant.

More than two-thirds of adults and one-third of children in the United States are overweight or obese. Obesity or being overweight may increase the risk of many health problems, including type 2 diabetes, heart disease, and certain cancers. If you’re pregnant, excess weight may lead to short- and long-term health problems for you and your child. Achieving a healthy weight, eating a healthy diet, and being physically active can help prevent these weight-related diseases.

Some people, in their efforts to lose weight, turn to unproven dietary supplements (sometimes marketed as “fat burners” or appetite suppressants), which can have harmful side effects. If you’re thinking about starting a new weight-loss program, talk with your health care provider, who can assess your weight and health risks, determine whether you need to lose weight, and provide information that will help you make informed decisions about an effective weight-loss program.

Bottom Line

• Most dietary supplements marketed for rapid weight loss, such as acai and hoodia, don’t work for keeping weight off in the long term, and some are dangerous. For example, ephedra, which was used in weight loss supplements, was banned because of unreasonable risk of injury or illness.
• Researchers have studied the weight loss potential of a variety of dietary supplements, including omega-3s and fish oil; chitosan, a dietary fiber from shellfish; green tea extracts; Chinese herbs; and bitter orange (Citrus aurantium) extract. None have been shown to be effective for weight loss, and each of these has side effects.
• There’s some emerging evidence suggesting that some mind and body approaches, such as yoga and meditation, particularly mindful eating, may be useful as complements to other weight-loss interventions.

Safety

• The U.S. Food and Drug Administration (FDA) banned the sale of dietary supplements containing ephedra, which was marketed for weight loss, because of serious health risks, such as cardiovascular complications and even risk of death. Ephedra is also called ma huang.
• Many ephedra-free supplements are now being sold, but side effects of some of their ingredients are similar to the banned products. Some ephedra-free supplements also have a lot of caffeine or herbs, such as guarana, that contain caffeine. The products can cause increased heart rate and abnormal heart rhythms.
• Many dietary supplements marketed for weight-loss (including ones sold as “fat burners” or appetite suppressants) have not been tested for safety.
• What’s on the label may not be what’s in the bottle. Analyses of dietary supplements, including herbal supplements, sometimes find differences between labeled and actual ingredients. Also, the FDA has found weight-loss products tainted with prescription drug ingredients.
• Dietary supplements for weight loss are sometimes misused by people with eating disorders, such as anorexia nervosa or bulimia nervosa, to lose weight or induce vomiting.
• If you’re considering a dietary supplement for weight loss, remember that “natural” does not necessarily mean “safe.”
• Mind and body practices, such as meditation and yoga, are generally considered safe for healthy people when practiced appropriately under the guidance of a well-trained instructor. If you have any underlying health conditions, talk to your health care provider about any complementary approach you may be interested in using.

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.

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 products.

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 pattern, 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.

Whether you’re looking to buy weight loss, male enhancement, or certain other products, these days you’re apt to look for them online, rather than at a physical store. 

But buyer, beware. When you buy such products, you may actually be getting an illegal product; and that product may contain potentially dangerous ingredients that are not on the label. 

This is not a new development. Over the past decade, the U.S. Food and Drug Administration (FDA) has frequently warned consumers that certain products sold over-the-counter (OTC)—including those sold over the “virtual” counter—contain hidden active ingredients that could be harmful. Hidden ingredients are a problem in products promoted for weight loss, body building, pain relief, sleep aids, and sexual enhancement. Often, products containing active ingredients in FDA-approved drugs  are falsely represented as dietary supplements. 

It is clear from the results of our decade of testing that retailers and distributors, including online marketplaces, do not effectively prevent these types of potentially harmful products from being sold to consumers.

FDA has also found products marketed as supplements with claims to treat or prevent serious diseases such as cancer, HIV, and COVID-19.  These products are typically unapproved drugs that have not been reviewed by FDA for safety or effectiveness, and consumers should not buy them.

What You Don’t Know Can Hurt You

Take weight loss and male enhancement products, for example. The FDA recently tested nearly 70 of these products found on Amazon, eBay, and Walmart.com, and discovered most of them contained active pharmaceutical ingredients not listed on the label. These hidden ingredients may interact with other drugs you are taking, or they may be associated with serious side effects.

All 29 of the products the FDA purchased on Amazon, and 20 of the 25 products (80%) purchased on eBay and half of the products purchased on Walmart contained undeclared active pharmaceutical ingredients. The FDA’s laboratory testing found the products contained various undeclared active ingredients, including sildenafil, tadalafil, vardenafil, sibutramine, desmethylsibutramine, phenolphthalein and/or fluoxetine. Most of these active ingredients are found in FDA-approved prescription drugs, including Viagra and Cialis; others were removed from the market for serious safety concerns.

How Can You Identify Dangerous Products?

It is easy for people to sell a potentially dangerous product online. We advise consumers not to purchase the  weight loss, sexual enhancement, body building, sleep aid, and pain relief products that are listed in the Public Notifications at the links above.   

If you are considering buying a product marketed as a dietary supplement, please go to the FDA’s tainted products database, where you will find nearly 1,000 of these potentially dangerous products listed. The agency updates the database as it finds new products that contain undeclared active pharmaceutical ingredients; however, new products and new websites pop up all the time, and it is impossible for the database to keep up. 

Even if a product has a different but similar name or is not in the list, you need to be cautious. Also watch out for products that are sold in one- or two-capsule packages that promise immediate results. The FDA works hard to identify and remove potentially dangerous products from the marketplace, but it’s a constant and ongoing effort. 

Steps to Take to Stay Safe

If you are thinking of using a product in one of these categories, talk to your doctor first. Ask your doctor for help in identifying reliable and credible information about the product. 

Do not take products that are sold without a prescription and claim to treat, cure or prevent a serious disease such as HIV or cancer. Products approved to treat or prevent serious diseases generally are prescription products, which are restricted to use under the supervision of a licensed health care professional.  

• Be cautious about trusting consumer reviews that include miraculous disease treatment and prevention claims. 
• Be aware of websites that direct you to online marketplaces to buy products. Claims regarding a product’s ability to prevent or treat a disease made on these websites have not been reviewed by FDA.  
• See BeSafeRx for information about how to safely buy medicine online. 

And finally, if you experience an injury from a product, do not just add a product review to the online marketplace; please also report your concerns to the FDA’s MedWatch Adverse Event Reporting program  so the agency can take any appropriate action to protect consumers from any unsafe products. Consumers are also encouraged to report unlawful sales of products sold online.

Although it’s easy to be tempted by the “quick fix” claims of dietary supplements marketed for weight loss, most of these products haven’t been proven safe or effective. If you’re thinking about taking a dietary supplement to help you lose weight, here are some things you should know.

1. Ask yourself if a product sounds too good to be true. Be cautious if the claims for the product seem exaggerated or unrealistic and use phrases like “quick and effective” or “totally safe.” Be skeptical about information from personal “testimonials” about the product’s benefits. Keep in mind that testimonials, anecdotes, unsupported claims, and opinions are not the same as objective, evidence-based information.

2. Be aware of the possibility of tainted products. The U.S. Food and Drug Administration (FDA) has found weight loss products sold as dietary supplements that contain hidden prescription drugs or other illegal ingredients. These tainted products can cause serious harm.

3. The science doesn’t support the use of acai berry, bitter orange, or green tea supplements for weight loss. None of these supplements has been shown to produce meaningful weight loss in scientific studies.

4. The safety of many weight loss supplements is uncertain. Many dietary supplements marketed for weight loss, including those sold as “fat burners” or appetite suppressants, have not been tested for safety.

5. The ingredients that replaced ephedra may not be harmless. In 2004, the FDA banned the sale of dietary supplements containing ephedra in the United States because of serious health risks. Other ingredients are now used instead, but some of them have side effects similar to those of ephedra. In addition, some supplements contain large amounts of caffeine or caffeine-containing herbs such as guarana, which may cause increased heart rate and abnormal heart rhythms.

6. Talk with your health care provider. If you’re considering a supplement marketed for weight loss, discuss it with your health care provider. Your provider can also help you choose an effective weight loss program. If your provider doesn’t bring up healthy eating, physical activity, and weight control during your regular checkup, you can start the conversation.