Dietary supplements for weight loss
Medically reviewed by Drugs.com. Last updated on Nov 10, 2020.
The promise of fast weight loss is hard to resist. But do weight-loss supplements lighten anything but your wallet? And are they safe?
What are dietary supplements?
Dietary supplements are sold as health aids. They're taken by mouth. Common ingredients are vitamins, minerals, fiber, caffeine, herbs and other plants.
Some of the most popular supplements claim to improve nutrition, boost energy, build muscle or burn fat.
Dietary supplements are not medicines. They aren't meant to treat or cure disease.
How are dietary supplements regulated?
Companies that make supplements are responsible for the safety of their products. They must ensure that their products are free of contaminants and that they're accurately labeled.
Dietary supplements don't require approval by the U.S. Food and Drug Administration (FDA). But if a supplement is found to be unsafe, the FDA can issue warnings or ask that it be withdrawn from the market.
The FDA can also take action against companies that make false or unsupported claims to sell their supplements.
Interpreting claims about weight loss
You might be surprised to learn that makers of dietary supplements rarely carry out clinical trials. That's part of the reason why there's little scientific evidence to show that weight-loss supplements work.
For example, raspberry ketone is marketed as a clinically proven weight-loss product. That claim is supported by one clinical trial.
The trial included 70 adults with obesity. All were placed on a restricted diet and exercise program. They were then randomly assigned to receive either a placebo or a supplement containing raspberry ketone, caffeine, bitter orange, ginger and garlic root extract.
The 45 people who completed the trial all lost weight:
- 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).
While these results are intriguing, the fact that the trial was small and lasted only eight weeks means the results can't be reliably generalized to real-world situations. And importantly, a short trial like this may miss side effects that only become apparent with long-term use.
In addition, the trial used a supplement that contained multiple ingredients. So it's impossible to tell which ingredient was responsible for the weight loss.
Ideally these initial results would be tested in a much longer trial involving hundreds of participants with careful monitoring for side effects. Results from such a trial would allow for an informed decision about the safety and effectiveness of such a product.
Until such trial data is more readily available, claims regarding dietary supplements and weight loss should be treated with caution.
Understanding safety concerns
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.
Supplements can have strong effects. Ephedra (ma-huang) is an herb once used for weight loss. It's now banned by the FDA because it was associated with adverse effects, such as mood changes, high blood pressure, irregular heart rate, stroke, seizures and heart attacks.
Some weight-loss supplements have been found to contain hidden ingredients, such as prescription drugs, that may be harmful.
Research before you buy
It's important to do your homework if you're thinking about trying a weight-loss supplement. Check credible websites, such as those run by the U.S. Office of Dietary Supplements and the National Center for Complementary and Integrative Health.
Also be sure to talk with your doctor before taking any supplement. This is especially important if you have health problems, take prescription drugs, or are pregnant or breast-feeding.