Supplements. Many over-the-counter supplements promise to help burn fat faster or reduce hunger. Some supplements have side effects that can be dangerous. A number of these products (perhaps most) have never been studied in clinical trials, so many of the side effects, benefits, and risks aren't well-documented. If the claim of the maker sounds almost impossible, it probably is. (For example, "Burn fat at night while you sleep!")
Ephedra (ma-huang) contains an ingredient used in asthma medication. Dietary supplements containing ephedra have been banned by the FDA because of potentially dangerous side effects.
Products that work as a laxative can cause the blood's potassium level to drop, which may cause heart and/or muscle problems. Pyruvate is a popular product that may result in a small amount of weight loss. However, additional ingestion of pyruvate, which is found in red apples, cheese, and red wine, hasn't been thoroughly studied. Its weight loss potential hasn't been scientifically established.
While there's no supplement that can take the place of eating a healthy diet, a multivitamin taken daily can help close the nutritional gap even for those people who eat a balanced diet. However, vitamin supplements don't produce weight loss.
Always consult with your health care provider before taking these supplements since they can cause a number of unexpected side effects.