Your Guide to Weight Loss Pills and Supplements

Find out which diet pills work and which supplements and medications to avoid

diet pills to lose weight
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Are you thinking about using a weight loss pill to slim down? Trying to find a medication or diet supplement that is both safe and effective can be challenging. Use this guide to sort through the facts to find the best diet pill to help you reach your goals.

How to Buy a Weight Loss Pill That Works

There are three different types of diet pills that you can buy. Prescription weight loss pills are medications that you would get through your doctor.

  Non-prescription or over-the-counter (OTC) diet pills are medications that don't require a prescription. And finally, there are herbal supplements for weight loss that you'll find in many vitamin shops and drug stores. Herbal supplements are not considered medications and therefore do not have to follow the strict guidelines for safety that govern our medicines.

The best resource for information regarding the use of any supplement or weight loss pill is your healthcare provider. Talk to your doctor about current research into the products that have grabbed your attention. Your doctor will also be able to discuss how taking a diet pill might interact with your other medications and will also be able to provide the best advice regarding the safety of new products.

Prescription Weight Loss Pills 

  • Xenical (orlistat). This prescription medication has been approved by the U.S. Food and Drug Administration (FDA) since 1999. Xenical is a lipase inhibitor which means it works by blocking the absorption of fat. Dieters must follow a low-fat diet or they experience uncomfortable side effects.
  • Qsymia (phentermine and topiramate)  The two drugs in Qsymia work together to suppress appetite and reduce your food intake.  Your physician may prescribe it if you have a BMI over 30 or a body mass index of 27 and higher along with a weight-related condition such as type 2 diabetes or high blood pressure. The medication needs to be taken along with lifestyle modifications for sustained weight loss.

  • Belviq (lorcaserin) This diet pill works by activating serotonin receptors that regulate hunger. By helping to control your appetite, drug makers hope that Belviq will help you feel full after you've eaten less food.  It is available with a prescription to patients with a BMI of 30 or a body mass index of 27 along with an obesity-related condition.

  • Saxenda (liraglutide [rDNA origin] injection) This injectable medication helps dieters to feel full sooner so that they eat less and lose weight. Saxenda can be used by patients who are obese (with a BMI of 30 or more) or by patients who have a BMI of 27 or more and a weight-related medical condition such as type 2 diabetes, high cholesterol or high blood pressure.

  • Contrave (naltrexone hydrochloride and bupropion hydrochloride) This weight loss drug affects the central nervous system to increase the number of calories you burn and reduce your appetite. The diet pill is prescribed along with a reduced-calorie diet and exercise program to help people lose weight.

  • Vyvanse (lisdexamfetamine dimesylate) This medication is FDA-approved for the treatment of binge-eating disorder, but it is not approved for weight loss.

  • Phentermine. Phentermine is marketed under a long list of names, including Suprenza, Adipex-P, Kraftobese and Teramine. It is prescribed only for short periods and works by decreasing a dieter's appetite. According to the ADA, it is the most widely prescribed diet pill in the United States. However, the drug can be habit forming; side effects can include insomnia, constipation and dry mouth.

  • Meridia (sibutramine). This appetite suppressant product was removed from the market in the United States in 2010. The FDA initially approved the product, but the manufacturer stopped producing it after clinical studies showed that users had an increased risk of heart attack and stroke. The National Institutes of Health (NIH) recommends that anyone still using Meridia contact their physician to discuss alternative treatments.

Non-Prescription Weight Loss Pills and Supplements

If you don't have a prescription for a diet medication, you might be tempted to take an over-the-counter (OTC) weight loss pill or a diet supplement. Keep in mind while OTC medications are FDA-approved for safety and effectiveness, weight loss supplements are not.  The FDA relies on the company that makes them to make sure that they are safe. So when you buy a diet supplement or a popular herbal supplement for weight loss you need to be very careful about what you buy.  The FDA also does not approve most of the claims that companies make about their products. In many cases, weight loss claims are carefully crafted to make the product sound more effective than it is.

  • alli (orlistat). This is the only over-the-counter weight loss pill approved by the FDA. It contains a lower dose of the same medication that is in Xenical. Dieters who take alli must limit fat intake and make lifestyle changes or they will experience uncomfortable side effects. alli was voluntarily removed from the market in 2014 after a tampering scare, but the company has re-released the diet pill with a new tamper-evident package.
  • Garcinia cambogia. This natural weight loss supplement is derived from a fruit that grows in warmer climates. It is widely available at health food stores and from online vendors, but many of the claims made by sellers have not been backed up consistently in published medical literature. One study published in Critical Reviews in Food Science and Nutrition said that there is still little evidence to support its effectiveness.
  • Glucomannan The name of this popular diet supplement may not sound familiar but you've probably seen products that contain the fiber supplement. Lipozene for weight loss is the most popular product that contains glucomannan. Unfortunately, the studies have been inconclusive and have not been able to confirm that the fiber substance can help you lose weight.
  • Conjugated linoleic acid (CLA)  This supplement has been studied extensively, but the results have been mixed.  Find out how much weight you can lose if you take CLA and check with your doctor before investing.  Some dieters experienced increased insulin resistance and lower levels of HDL cholesterol when taking the diet pills.
  • Raspberry ketones This weight loss supplement became popular after Dr. Oz mentioned it on his TV show. But there has been no evidence to support the claims that raspberry ketones can help humans lose weight.
  • Forskolin This natural extract from the coleus plant is advertised as a diet supplement and fat blocker. But very few studies have been done so there is very little evidence to support its use as a weight loss supplement.
  • Ephedra or Bitter Orange When ephedra was banned from the market in 2004, a number of similar stimulants took its place. Most advertise that they are ephedra-free and safe for dieters. They often contain bitter orange (citrus aurantium), synephrine or octopamine. Two of the most popular products, Xenadrine EFX and Advantra Z, were tested by researchers and still found to have unsafe effects on heart rate and blood pressure.
  • Chromium. Sometimes marketed as chromium picolinate, products that contain this substance often claim to help you burn extra calories and decrease your appetite. However, the NIH found that chromium has no significant benefits for weight loss. Chromium is generally considered to be safe, but it is likely to drain your wallet without any significant benefit to your waistline.
  • Green tea. Green tea can be consumed as a beverage or in pill form. It is often used to aid in weight loss or for improving mental alertness or lowering blood pressure. While green tea is safe when consumed in moderation, there is little evidence to support its use as a long-term weight loss supplement.
  • Hoodia. This herb is sold as a hunger suppressant for dieters. Hoodia is extracted from a flowering plant and can be consumed in tablet, pill or powder form. There is no scientific evidence to support the claims that hoodia is an effective appetite suppressant and its safety has not been verified.
  • Bee pollen. There is little evidence to support the use of bee pollen for weight loss.  In fact, the medical experts at say that bee pollen is not safe or effective. One company was recently cited by the Centers for Disease Control for making false and misleading claims about the supplement's effects.

If the weight loss pill that you are interested in is not listed above, visit the National Institutes of Health Dietary Supplement Fact Sheets website.  The NIH provides a comprehensive list of diet supplements along with current information about safety and effectiveness. And remember to talk to your doctor about any diet pill or weight loss supplement that you are considering.


Chromium. Office of Dietary Supplements, National Institutes of Health. Accessed: November 28, 2011.

Heidi Michels Blanck PhD, Mary K. Serdula MD, Cathleen Gillespie MS, Deborah A. Galuska PhD, Patricia A. Sharpe PhD, MPH, Joan M. Conway PhD, RD, Laura Kettel Khan PhD, Barbara E. Ainsworth PhD. "Use of Nonprescription Dietary Supplements for Weight Loss Is Common among Americans." Journal of the American Dietetic Association March 2007, Pages 441-447 . Weight Management. American Dietetic Association. Accessed: December 15, 2011.

Sharpe PA, Granner ML, Conway JM, Ainsworth BE, Dobre M. "Availability of weight-loss supplements: Results of an audit of retail outlets in a southeastern city." Journal of the American Dietetic Association. 2006 Dec;106(12):2045-51.

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Weight Control Information Network. "Choosing a Safe and Successful Weight Loss Program". U.S. Department of Health and Human Services, National Institutes of Health. Accessed: November 28, 2011.

"Weighing the Evidence in Diet Ads". Federal Trade Commission. Accessed: November 28, 2011. Government PDF

"Dietary Supplements For Weight Loss. Limited Federal Oversight Has Focused More on Marketing than on Safety." Janet Heinrich
Director, Health Care-Public Health Issues. Accessed: November 25, 2011. Government PDF

Amelia Hollywood and Jane Ogden. " Taking Orlistat: Predicting Weight Loss over 6 Months." Journal of Obesity October 2010 .

Green Tea. National Institutes of Health, National Center for Complimentary and Alternative Medicine.. Accessed: November 28, 2011.

Hoodia. National Institutes of Health, National Center for Complimentary and Alternative Medicine. Accessed: November 25, 2011.

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