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Weight loss supplements: What you need to know

Last Modified: 1/07/2019

For many, the new year means weight loss goals. If supplements are part of your strategy, there are some things you need to know about the risks and the possible benefits. We invited Jennifer Tompkins, PharmD Candidate 2019, Butler University College of Pharmacy and Health Sciences, with input from Tim Johnston, PharmD, BCPS, BCCCP, Parkview Regional Medical Center, to explore the topic.

Healthy weight loss

Unfortunately, there is no quick fix to weight loss. Cutting corners may not only be ineffective, but also harmful to your overall well-being. Weight loss is not easy. The healthy changes that can lead to the desired results are tactics that should truly become part of your ongoing lifestyle. Positive changes to your diet and exercise need to be consistent, not just done here and there. Before making any serious changes, consult your healthcare provider to discuss personal health goals and recommendations tailored to you.

The benefits of weight loss

Believe it or not, there’s more to weight loss than looking good at the beach. In fact, the long-term health benefits far outweigh the short-term ones. Living a healthy lifestyle decreases your risk of type 2 diabetes, stroke and heart diseases. After you shed a few extra pounds, decreased joint pain and back pain will improve your mobility, allowing you to continue to be active. Along with physical benefits, you will see a boost in your mental state as well. Weight loss can increase your energy and self-body image, while decreasing your stress level.

What are weight loss supplements?

Weight loss supplements are dietary supplements that may aid in the reduction of a person’s weight. Because these are dietary supplements, other lifestyle changes such as diet and exercise are essential to promote weight loss. Dietary supplements should not be used as the primary source of weight control.

How they work

There are three primary functions of weight loss supplements: reducing appetite, reducing absorption of nutrients like fats, and increasing fat burning. More and more weight loss supplements are out on the market each day. It can be overwhelming deciding which one is best for you, so it’s important to know the different ways in which they work. They’re not all created equal. Certain supplements may cause side effects or interact with current medications. If you are considering using a weight loss supplement, make sure to do plenty of research. Consult a healthcare provider to discuss potential risks and benefits before making a final decision.

Commonly used weight loss supplements

These are some of the most common supplements, their use, efficacy and notes on safety.

Orlistat (Alli™)

Use: Orlistat works by reducing the absorption of fats by inhibiting the breakdown of dietary fat. With the reduced absorption, the dietary fats are excreted as oil in the stool.

Efficacy: Evidence of favorable outcome is available for use of Orlistat. Xenical™, is the brand of Orlistat that is available as a prescription product. The OTC product provides 80 percent of the weight loss seen with the prescription.

Safety: May cause diarrhea, stomach pain, and difficulty controlling bowel movements. Following a low-fat diet is recommended to minimize side effects.

Garcinia Cambogia Extract

Use: Garcinia cambogia is a fruit-bearing tree and the fruit’s pulp and rind contain high amounts of hydroxycitric acid. Hydroxycitric acid may reduce appetite and inhibit the formation of fats.

Efficacy: Uncertain, as human studies have been conflicting.

Safety: May have mild adverse effects, including headache, nausea, and upper respiratory tract symptoms. Some studies have reported cases of mania, irritability and liver toxicity. Long term effects are unknown.

Caffeine, Hydroxycut™, Green Coffee Bean Extract, and Green Tea Extract

Use: Caffeine stimulates the central nervous system, heart and skeletal muscles which can boost metabolic rate and increase fat burning.

Efficacy: Studies have shown a reduction in body mass index (BMI). Habitual use may lead to tolerance and diminish effects.

Safety: The American Medical Association recommends a limit of 500 mg/day of caffeine. Can cause sleep disturbances, tremors and jitteriness. Can be toxic above 15 mg/kg (about 1000 mg for a 150 lb adult) and cause an elevated heart rate, nausea, vomiting and seizures.


  • Use: Glucomannan is a soluble dietary fiber that can absorb 50 times its weight in water. Has been proposed to reduce appetite and prolonged gastric emptying by absorbing water in the GI tract.
  • Efficacy: Little efficacy shown for weight loss
  • Safety: Well tolerated for short-term use with minor adverse effects including belching, bloating, flatulence, diarrhea, constipation, and abdominal discomfort. The capsule form is recommended over tablets due to additional safety risks.


Use: Forskolin is found in the roots of the Coleus forskohlii plant which may promote weight loss by increasing fat burning through reducing appetite and increasing the breakdown of fats.

Efficacy: Research is limited and inconclusive, but could be effective in reducing the mean body fat, not the body weight

Safety: May cause diarrhea.

Bitter orange

Use: Bitter orange, also known as Citrus aurantium, contains the compound synephrine, which may reduce appetite, boost metabolic rate and increase fat burning.

Efficacy: Research is limited for bitter orange alone, as it is almost always combined with other weight-loss supplements in studies.

Safety: Products containing bitter orange are not recommended. Associated adverse effects include chest pain, elevated heart rate, headache, and heart attack.

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