The Secrets to Avoiding Dangerous Weight-Loss Supplements

By Pieter Cohen, MD, Cambridge Health Alliance, Harvard Medical School

Posted on | By Pieter Cohen, MD

Buying a natural weight loss supplement in a local store provides a sense of security. The well-lit store and friendly clerk – not to mention the sales tax – suggests that these weight-loss pills have Uncle Sam’s blessing. We shouldn’t blame ourselves for thinking that if they were really dangerous someone would have already removed them from US stores. Unfortunately, this is a false sense of security as dangerous weight-loss supplements are found on store shelves throughout America.

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Instead of the herbal ingredients listed on the label, these dangerous supplements actually contain unlisted, banned drugs. The US Food and Drug Administration (FDA) has warned that hundreds of supplements contain hidden illegal drugs. These drugs pose real health hazards. The most common pharmaceutical in weight-loss supplements – sibutramine – can cause heart attacks and strokes even when physicians carefully prescribed it for weight loss.  That’s why the FDA banned sibutramine in 2010. But the risks multiply when we unknowingly use weight-loss supplements illegally spiked with the same drug. The drug is no longer produced by a professional pharmaceutical company, but instead by criminals in illegal factories without any quality control whatsoever.  Not only is the quality poor, but the amount of drug in each pill is completely unpredictable. One supplement pill can contain six-times more sibutramine than in one prescription pill. The poor quality and unpredictable dosages increase the health risks of the hidden pharmaceuticals.

Unfortunately, banned drugs are only the tip of the iceberg. Even more alarming are entirely new chemical substances that have never been tested in humans. The manufacturer starts with a banned medication, tinkers with the chemical structure by breaking a bond or switching a molecule, and creates a new substance. This new molecule has never been tested in animals, much less humans. The side effects of these new drugs may be similar to those of the parent drug – heart attacks and strokes – or they might be entirely different life-threatening effects. While the supplement label lists only herbal ingredients, the supplement capsules actually contain a new chemical. The manufacturer hopes that the new chemical leads to weight loss while remaining under the regulatory radar screen. The manufacturer has done nothing to ensure safety; instead, they are performing their own experiments, and American consumers are the guinea pigs. 

Tragically, we don’t have to wait to know if these experiments are deadly. In Europe, dieters have already died from using weight-loss supplements with modified prescription drugs. 

In a game of cat and mouse, the FDA tries to find these supplements spiked with pharmaceutical products while manufacturers find new ways to conceal them. When the FDA finds the spiked products, it issues alerts and requests that distributors recall the products. But this approach is not working.  Due to limited resources and an overwhelming number of new supplements on the market, the FDA can only find a small percentage of the dangerous, spiked supplements that are sold on store shelves. Even when they do find the spiked supplements, the FDA alerts and recalls may have little effect on sales. 

We recently studied the sale of Pai You Guo, a supposed herbal weight-loss supplement which is actually spiked with sibutramine. We found that sales of Pai You Guo from local stores continued well after the FDA warned that the product contained sibutramine and could cause heart attacks and stroke. Even after the FDA discovered Pai You Guo contained hidden pharmaceuticals, the weight-loss supplement remained readily available on local store shelves.

With these dangerous supplements camouflaged as natural products in local stores and sold by friendly clerks (who themselves have no idea what they are actually selling), how can you avoid the dangerous weight-loss supplements? Even though there are hundreds of supplements for weight loss, the choice is surprisingly easy. The truth is that no weight-loss supplement actually helps you safely lose weight. 

According to the Natural Medicines Comprehensive Database, a premiere academic reference on herbal treatments, not a single herbal ingredient is safe and effective for weight loss. On the other hand, any supplement can legally be marketed as increasing metabolism or burning fat. The current law permits companies to label a supplement as a fat destroyer even if there isn’t a single human study to support the claim. This explains why one day we hear that seaweed is effective for weight loss then the next day glucomannan, then guggul. Since anything can be labeled as a metabolism aid, hundreds of products are on sale for weight loss – but they are not safe and effective.

How could it be that no herbal ingredient can help you safely lose weight if your friend swears by a favorite product? We all know someone who has lost 10 or 20 pounds taking a weight-loss supplement and swears by it. The problem is that if a supplement does lead to weight loss, the chance it contains hidden, illegal medications increases dramatically. Weight-loss supplements come in only two varieties: those that don’t work and those that are potentially dangerous. Since weight-loss supplements are either ineffective or hazardous, they should all be avoided. Hopefully, future research will discover an effective and safe weight-loss supplement but that doesn’t exist yet. So, I recommend walking right past the weight-loss aisle and spending the money instead on high quality food and a new exercise outfit.

Article written by Pieter Cohen, MD
Cambridge Health Alliance, Harvard Medical School