Over-the-counter weight-loss pills

The temptation to use over-the-counter weight-loss pills to lose weight fast is strong. But are these products safe and effective?

By Mayo Clinic Staff

The appeal of losing weight quickly is hard to resist. But do weight-loss pills and products lighten anything but your wallet? And are they safe?

Setting realistic expectations

There's no magic bullet for losing weight. The most effective way to lose weight and keep it off is by eating a healthy low-calorie diet and being more physically active.

Weight-loss pills — prescription drugs, nonprescription drugs, herbal products or other dietary supplements — are all, at best, tools that may help with weight loss. But there is relatively little research about these products. The best studied of these are prescription weight-loss drugs.

For example, a 2016 study reviewed 28 long-term trials of prescription drugs for treating obesity. The researchers concluded that when a person makes appropriate lifestyle changes, a prescription weight-loss drug increases the likelihood of achieving "clinically meaningful" weight loss within a year.

Clinically meaningful weight loss means you've lost enough weight to lower your risk of heart disease, diabetes and other diseases. This is generally defined as 5 percent or more of body weight.

It's important to consider that weight loss achieved in a research setting may be greater than in actual practice. Also, possible side effects and adverse reactions to weight-loss pills can affect how well you might do.

It's reasonable to expect that prescription weight-loss pills may be beneficial, but they won't be magical. They don't work for everyone, and the benefits may be modest. Researchers know much less about the potential benefits and risks of over-the-counter weight-loss products.

Understanding over-the-counter treatment regulations

Over-the-counter weight-loss treatments fall into two general categories:

  • Nonprescription drugs
  • Dietary supplements

The standards for regulating the production and marketing of these two types of treatments are different. For a nonprescription drug, such as orlistat (Alli), the drug company must provide the Food and Drug Administration (FDA) with results from human (clinical) trials that show the safety and effectiveness of the drug at the nonprescription dose.

The makers of dietary supplements are responsible for ensuring the safety of their product and making honest claims about possible benefits. However, the makers' claims aren't subject to FDA review or approval before marketing. Also, the type or quality of research used to support claims can vary.

If the FDA can demonstrate that a supplement is unsafe, the agency can ban the product or ask a manufacturer to withdraw it voluntarily. The FDA may also take action against a manufacturer if there is no evidence at all to support a claim.

These differences in research, production and marketing can make it difficult to make informed decisions about products.

Interpreting claims on weight-loss supplements

When a dietary supplement is marketed as "clinically proven" to cause weight loss, there should be some type of clinical evidence to support it. Such a claim, however, provides no details about the clinical research.

For example, raspberry ketone supplements are marketed as clinically proven, natural weight-loss products. As of December 2017, the results of only one clinical trial with raspberry ketone had been published. The results include the following information:

  • The eight-week trial used a multi-ingredient supplement with raspberry ketone, caffeine, bitter orange, ginger root extract and garlic root extract, as well as other herbs, vitamins and minerals.
  • Seventy obese adults were randomly assigned to receive either the supplement or an inactive ingredient (placebo).
  • All of the participants were placed on a restricted diet and exercise program.
  • Forty-five people completed all eight weeks of the trial.
  • Among people completing the trial, the average weight loss in the supplement group was 4.2 pounds (1.9 kilograms).
  • The average weight loss in the placebo group was 0.9 pounds (0.4 kilograms).

The weight loss in the treatment group was modest, and the trial was only eight weeks, which isn't long enough to know if the supplement will help with weight loss long term. Plus, the supplement included multiple ingredients, making it impossible to judge which ingredients helped the weight loss.

Understanding safety concerns

Limited research also makes it difficult to judge the safety of a weight-loss supplement. And a product isn't necessarily safe simply because it's natural. Though rare, some dietary supplements have been linked to serious problems, such as liver damage.

Ephedra, or ma-huang, is an herbal stimulant once used in weight-loss products. It's now banned by the FDA because of possible adverse effects, including mood changes, high blood pressure, irregular heart rate, stroke, seizures and heart attacks.

Bitter orange is a currently available herbal stimulant used in some weight-loss supplements and is often called an ephedra substitute. The active ingredient in bitter orange has chemical properties and actions that are similar to ephedra and may be associated with similar adverse effects. Because of limited research and the use of bitter orange in multi-ingredient supplements, the safety of the product isn't well-understood.

Researching before you buy

It's important to do your homework if you're thinking about trying over-the-counter weight-loss pills. Information about many dietary supplements is available online from the Office of Dietary Supplements and the National Center for Complementary and Integrative Health.

The Natural Medicines database summarizes research regarding dietary supplements and herbal products. Although information from the Natural Medicines database is available only by subscription, you may be able to access it through a public library.

Including your doctor in your weight-loss plans

If you're considering weight-loss pills, be sure to talk with your doctor, especially if you have health problems, take prescription drugs, or are pregnant or breast-feeding. It's also important to get advice on possible interactions with your current use of medicine, vitamins or minerals.

Your doctor can also offer advice on losing weight, provide support, monitor your progress or refer you to a dietitian.

Feb. 06, 2018 See more In-depth