If you’re trying to lose weight, chances are you’ve wished for a faster and easier solution than long-term dieting and exercise. Weight loss pills and supplements may seem like the answer for quick and low effort weight loss. But they are usually only slightly effective at best, and at worst they can be dangerous for your health.

Weight loss supplements and their manufacturers promise miracles, but often they don’t deliver. Most studies on supplements, even ones done by the manufacturers, show only modest results. Melinda Manore, a professor at Oregon State University, looked at the studies done on a variety of supplements, including ones that are supposed to block the absorption of fat or carbs, boost metabolism, change your body composition to reduce body fat, and suppress your appetite, so you eat less. She wrote that on average when participants did have weight loss with any of these types of supplements, it was typically only four to seven pounds over months-long studies.

If you’re looking into weight loss supplements, chances are you’re hoping for more dramatic weight loss. Only about 9% of people in supplement studies reached their weight loss goal and were able to keep the weight off, while most people who lose weight with supplements gain it back. Thirty percent don’t lose any weight at all.

Why are so many supplements falling short for weight loss?

One factor is that many of their ingredients aren’t thoroughly tested and might not have any real weight loss benefits at all. Supplements aren’t regulated by the FDA in the same way as over the counter and prescription drugs, so they don’t need to prove that their ingredients are effective before going on the market. When a supplement says “clinically tested” or “clinically proven” on the label, there might only be one or two small studies on its effects, and these studies are often commissioned by the manufacturers themselves. Often supplements contain a mix of ingredients beyond the main ones they advertise, so it can be hard to tell which, if any, are affecting people’s weight.

On top of using ingredients that haven’t been proven effective, supplement labels may not be accurate to what’s inside. Since their products aren’t officially regulated, it’s easier for companies to lie about ingredients. That means that the supplements you take might not even have the weight loss ingredients they advertise, or they can have other potentially harmful ingredients.

Interfere with Medications

Non-prescription supplements can also interfere with other medications you’re taking, especially if they contain hidden ingredients. A lot of supplements are designed to change your metabolism and how you absorb food. Not only do these changes affect how you take in food, but they also change how you absorb your medications. You may be getting too much or too little out of the same pills you usually take without even realizing it.

The FDA has found that many dietary supplements contain hidden ingredients that are also found in prescription drugs. They issued warnings on 12 weight loss supplements in 2017, and so far in 2018, they’ve published another eight. For example, several weight loss products were found containing the ingredient sibutramine, which is one of the active ingredients in the prescription weight-loss drug Meridia. Meridia was taken off the market in 2010 for causing heart attacks, strokes, and other cardiovascular issues.

The supplements Oxyelite Pro, Sport Burner, and potentially other similar products contain the active ingredient from Prozac (fluoxetine), a prescription antidepressant. Some “water pills” designed to reduce bloating from water weight have a serious diuretic called triamterene which is also prescription-only. On top of these, the FDA found ingredients from prescription medication for seizures and blood pressure in other weight loss products. Even some products labeled as “natural” or “herbal” may have these or similar ingredients added.

Dangerous Side Effects

Popular natural weight loss products can also have dangerous health side effects on their own. Bitter orange is a common supplement ingredient made from the fruit of the bitter orange tree. Its scientific name is Citrus aurantium. Bitter orange contains the compound synephrine, a stimulant, which is usually used to increase your metabolism and suppress your appetite for weight loss. Synephrine has the risk of increasing your heart rate and raising your blood pressure, putting you at a higher risk of cardiovascular issues. In extreme cases, you could be at risk for a heart attack or stroke.

Synephrine is similar to another naturally derived stimulant also used to be used as a weight loss supplement that has been banned by the FDA for its dangerous side effects. Ephedra, also called ma-huang, was banned in 2003 after over 16,000 reports of health problems caused by the drug. Doctors at the Mayo Clinic recommend skipping bitter orange because this risk outweighs its potential weight loss benefits. Many other naturally derived and man-made weight loss supplements use stimulants to boost metabolism and decrease appetite. These treatments may also have serious cardiovascular effects.

The ban on ephedra also helps explain why it can be so difficult to tell if the supplements available in stores and online are safe. The FDA typically only bans supplement ingredients after there have been significant cases of it causing serious problems. That means that dangerous ingredients can stay on the market for longer and that their users have to experience major side effects before they’re pulled from the shelves.

Supplements can get in the way of your weight loss goals by discouraging you from more proven methods for dropping pounds. The nutrition researcher Melissa Manore confirms that the most reliable keys to weight loss are a lower calorie diet with fruits, vegetables, and lean protein, combined with staying active. Healthy lifestyle changes will help you keep the weight you lose off for the long haul, without the risk of side effects from untested ingredients.

Most weight loss supplements, manmade and natural, are unlikely to help you lose weight and may pose a threat to your health with hidden and unsafe ingredients. Diet changes and exercise remain the keys to healthy and safe weight loss.