We’ve all seen television, magazine and Internet advertisements promoting “miracle” weight-loss supplements. Of course it sounds very appealing to take an herbal product that melts away 25 pounds in two weeks. However, these so-called “natural” weight-loss supplements are not subjected to regulation to be marketed in the U.S. Unlike prescribed drugs, natural or herbal supplements are not required by regulatory authorities to be proven as safe or effective before they can be purchased.

So, what exactly is considered a weight-loss supplement? A weight-loss supplement is a substance that is a naturally occurring plant and not illegal. Lax legislation allows commercialization of these supplements as long as they don’t include words like “cure” or “treat,” otherwise they will fall into a drug category.

Are these supplements’ claims sound medicine or simply malarkey? Let’s take a look:

Hoodia (hoodia gordonii)

  1. A cactus-like plant found in South Africa, hoodia is used by the region’s indigenous people as an appetite suppressant while on long hunting trips.
    Fact or fiction: Fact
  2. Hoodia is a powerful plant with a miracle ingredient which could help us all become thin once again.
    Fact or fiction: Fiction
    In 1998, the active ingredient in hoodia was isolated. It was called p57. A small clinical trial did show a mild reduction on the average daily calorie intake.
    The trial only lasted two weeks, which is too short to show significant weight changes.
  3. Hoodia products have super concentrated amounts of extract to maximize their potency.
    Fact or fiction: Fiction
    Hoodia extract is extremely difficult to synthesize. As of 2003, drug development on hoodia was abandoned. Multinational consumer goods company Unilever had attempted to create foods containing hoodia, but after a substantial investment, the company abandoned the project, saying that the manufacturing plant did not meet standards for safety and efficacy.
  4. Hoodia products contain real South African hoodia.
    Fact or fiction: Likely fiction
    The trade of hoodia is tightly regulated, as it is protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora treaty. For instance, an investigation revealed that the product “P57 Hoodia” was tainted. It contained sibutramine, a controlled weight-loss drug that was removed from the market in 2010 due to its association with increase risk of heart disease and stroke. Other products advertised as containing hoodia have also been found to contain derivatives of other cactus-like plants, but no hoodia.

Garcinia cambogia (Garcinia gummi-gutta)

  1. Garcinia is a small, sweet, tropical tree fruit shaped like a pumpkin and is native to Indonesia.
    Fact or Fiction: Fact
    The dried rind of Garcinia has been used for centuries in Southeast Asia as a food preservative and flavoring agent.
  2. Garcinia is the Holy Grail for weight loss.
    Fact or fiction: Fiction
    Dr. Oz made the above claim in 2012. Several small human studies about the effects of garcinia do exist. A study involving 135 participants showed no difference in weight between the ones who took garcinia versus those who took a placebo (a “dummy’ pill with no medicinal ingredients). People who took garcinia reported more headaches and diarrhea.
  3. To be effective, garcinia products should have 60 percent of hydroxycytic acid (HCA), the active ingredient in garcinia.
    Fact or Fiction: Fiction
    There is no scientific evidence to support which concentration of HCA is safe. Growing cases of liver toxicity led the FDA to recall one of the best-selling garcinia products (Hydroxycut) in 2009. Some cases led to the need for liver transplant and death.

Green Coffee Extract (GCE)

  1. Green coffee extract is an extract of unroasted green coffee beans.
    Fact or fiction: Fact
    GCE contains small amounts of chlorogenic acid, a molecule also found in fruits and vegetables that has been shown to have antioxidant properties.
  2. Green coffee extract will make you thin faster.
    Fact or fiction: Fiction
    Studies testing the effect of GCE have been small and of poor quality. For example, in one study with 62 participants, a mild decrease in weight (2.4 Kg) in those that took the coffee bean extract when compared to people who took a dummy pill was observed. Small studies are prone to high variability and bias so the clinical significance of this mild weight loss is unclear. By comparison, studies involving any of the current FDA-approved weight loss drugs included over 3,000 people. These studies were randomized and controlled, which yield the highest quality of evidence. Side-effects of consumption of GCE in large quantities are not known.
  3. Green coffee extract results in weight loss without eating less or exercising more.
    Fact or fiction: Fiction
    These claims have been recently deemed deceptive and not supported by scientific evidence. In January 2015, Lindsey Duncan, a self-described “celebrity nutritionist” representing companies selling green coffee bean diet supplements under the labels Pure Health LLC and Genesis Today, Inc. made the above claim. In response, the Federal Trade Commission filed charges of deceptive advertising, and the companies have agreed to pay $9 million in refunds to people who bought the supplements and refrain from making any weight-loss claims unless substantiated with studies.

Green tea (camellia sinensis)

  1. Numerous scientific studies have shown that those who drink green tea lose weight faster.
    Fact or Fiction: Fiction
    A meta-analysis including 14 weight-loss studies showed that green tea appears to induce minimal weight loss in obese and overweight adults that likely has no clinical significance.
  2. It is healthy and safe to consume green tea everything.
    Fact or Fiction: Fiction
    We can fill our shopping cart with green tea ice cream, noodles, extracts and other so-called super foods, however, studies have shown that overconsumption of green tea (the equivalent of 5 liters of tea a day) can cause nausea, diarrhea, vomiting, agitation, confusion, palpitations and liver toxicity.

THE VERDICT: Due to their marginal or complete lack of effectiveness, heavily promoted weight-loss supplements can present a real risk due to the lack of regulation. Incorrect and misleading labeling, unproven effects, suboptimal manufacturing practices and the high risk of buying products that are often tainted are not worth the money invested or the risk of serious adverse health effects. The best course of action for losing weight is to invest in professional advice from a registered dietitian or join a structured weight management program.

For more information on this topic, please read the FDA warning about products promising weight loss on Also, disclose all herbal supplements you are taking to your doctor.

Dr. Paulina Cruz Bravo is currently a second-year Fellow in Endocrinology at Washington University in St. Louis, Missouri. Dr. Cruz is interested in understanding the pathophysiology of obesity and diabetes. She is also committed to help her patients achieve a healthier weight. She has been published in peer-reviewed medical journals including Obesity and the American Journal of Cardiology. Dr. Cruz will join the clinical faculty at Washington University at the conclusion of her fellowship.