Diet supplements, often referred to as "diet pills", are prescription or over-the-counter products that claim to help users lose weight. The supplements are often in pill or capsule form, but can also be consumed in other forms, such as teas.http://www.ucdmc.ucdavis.edu/medicalcenter/healthtips/2010-2011/07/20100729_diet-pills.html Diet supplements often work by increasing the metabolism of those who consume them, or by inhibiting the body's ability to absorb fat.http://www.ucdmc.ucdavis.edu/medicalcenter/healthtips/2010-2011/07/20100729_diet-pills.html Only one OTC diet supplement, Alli, has been approved by the U.S. Food and Drug Administration for weight loss. http://www.myalli.com/About_alli/FDA_approved.aspx

Studies have found that the effectiveness of diet supplements varies widely between users, indicating that not any one supplement will work for everyone. One study that investigated people who have dieted successfully found that only four percent of the study's participants did so with the use of supplements.http://www.ucdmc.ucdavis.edu/medicalcenter/healthtips/2010-2011/07/20100729_diet-pills.html Medical professionals and nutritionists recommend that weight loss programs that use diet supplements also include changes to participants' eating and exercise habits. Ultimately, to effectively lose weight, a person needs to consume fewer calories than they expend.http://www.ext.colostate.edu/pubs/foodnut/09363.html

Some diet supplement ingredients have been banned by the Food and Drug Administration, such as phenylpropanolamine (or PPA) and ephedrine or ephedra.http://www.ucdmc.ucdavis.edu/medicalcenter/healthtips/2010-2011/07/20100729_diet-pills.html Phenylpropanolamine was found to increase the risk of stroke, and ephedrine's side effects include increased blood pressure, and an increased risk of heart attack, stroke and seizure.http://www.ext.colostate.edu/pubs/foodnut/09363.html Some common diet supplement ingredients and their possible side effects:

• Chitosan supplements: Digestive upset including diarrhea and gashttp://www.ext.colostate.edu/pubs/foodnut/09363.html
• Green tea extract supplements: Contains caffeine, which can lead to restlessness, insomniahttp://www.ext.colostate.edu/pubs/foodnut/09363.html
• Dietary teas: Are often laxatives, can cause intestinal pain and dependency on them can lead to constipationhttp://www.ucdmc.ucdavis.edu/medicalcenter/healthtips/2010-2011/07/20100729_diet-pills.html
• Alli: Contains Orlistat, which can cause frequent bowel movements and bloatinghttp://www.duke.edu/~mtr4/diet-research/
• Fastin: Contains phenylethylamine, found in chocolate. can lead to restlessness, insomniahttp://www.duke.edu/~mtr4/diet-research/