The Scoop on Natural Weight Loss Supplements

Green tea in two japanese ceramic cups
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For weight loss to be sustainable, you have to have a plan you can realistically keep up with. Given all the time and effort that goes into exercising and changing how you eat, natural supplements can be appealing because they seem like an easy way to slim down.

However, diet supplements are not regulated by the U.S. Food and Drug Administration (FDA), and most of them have little scientific evidence to back up their weight loss claims. Some weight loss supplements have been found to contain banned ingredients (including ephedra). These products may have serious medical side effects, like liver injury.

Here's what you need to know about the most common ingredients in natural weight loss supplements. This information can help you make an informed decision if you choose to try them out.

Apple Cider Vinegar

Despite the claims, there is limited evidence that acetic acid, found in apple cider vinegar (and other types of vinegar), can suppress your appetite. A 2019 study published in the journal Nutrients found that while acetic acid is potentially helpful in regulating blood sugar, researchers noted that more studies are needed. There's very little evidence to support that taking apple cider vinegar supplements can help you lose weight.

Normal amounts of apple cider vinegar in cooking shouldn't pose a problem for most people. However, there are some concerns that larger amounts of undiluted apple cider (taken in pill or liquid form) can injure the esophagus and digestive tract.


A dietary supplement made from chitin (a substance found in the shells of crabs, shrimp, lobster, and other crustaceans), chitosan is said to bind to dietary fat in the intestines.

Although supplement manufacturers claim that chitosan can block fat absorption, a 2003 study found little evidence to support it as an effective form of weight loss treatment.

Chitosan may cause allergic reactions if you have a shellfish allergy. It has also been known to cause side effects such as bloating, gas, constipation, indigestion, heartburn, and nausea.

Conjugated Linoleic Acid (CLA)

A supplement containing compounds found in a fatty acid called linoleic acid, conjugated linoleic acid (CLA) is often marketed as a weight loss aid.

Although proponents of the supplement claim that CLA may decrease fat while building muscle, research results have yielded mixed results and insufficient evidence.

Possible side effects of CLA include abdominal discomfort, constipation, nausea, and loose stools. Some sources caution against long-term use due to possible adverse effects on blood lipids and glucose.


Fucoxanthin is an antioxidant found naturally in edible brown seaweed like wakame (a form of seaweed used in miso soup).

Although supplement manufacturers claim that fucoxanthin can increase energy expenditure and inhibit the buildup of abdominal fat, clinical human trials testing the effects of fucoxanthin (and the safety) are limited.


Glucomannan, a soluble fiber-rich substance extracted from the root of the konjac plant, has gained popularity as a weight-loss aid. Proponents of glucomannan claim that it suppresses appetite because the soluble fiber attracts water and turns to gel during digestion.

While there's some preliminary evidence suggesting the glucomannan may increase feelings of fullness, it's too soon to recommend the supplement for weight loss.

Glucomannan can potentially affect blood sugar, so it's not recommended if you have diabetes. The supplement (particularly in tablet form) can also pose a risk of choking or a blockage in your digestive tract.

Green Tea

There is some research indicating that substances in green tea, such as theanine, may raise your metabolism and curb your appetite. However, the overall research findings have been mixed.

Taking a green tea supplement might not help you with weight loss (and the caffeine content may be a problem for some), but the benefits of green tea may support your efforts as part of a healthy eating plan.


Hoodia is a cactus that grows in the Kalahari desert in Africa. It was traditionally used by Bushmen to curb their hunger and thirst. Although supplement marketers claim that it can reduce appetite, there's very little published research in humans.

Fake hoodia is also a problem (many counterfeit hoodia products have been marketed and sold as the real thing).

Adverse effects include headache, nausea, vomiting, and dizziness. It may also raise blood pressure and heart rate.

Raspberry Ketones

The chemicals that give red raspberries their sweet scent, raspberry ketones, are also sold in dietary supplement form. Proponents claim that raspberry ketones can promote weight loss by triggering the breakdown of fat cells.

Although some animal-based studies suggest that raspberry ketones may offer some anti-obesity benefits in animals, there's no solid evidence that it can support weight loss in humans.

The National Institutes of Health indicates that safety and adverse side effects of raspberry ketones are not yet known since research on humans is still too limited.

White Bean Extract

Typically marketed as a "starch blocker," white kidney bean extract (Phaseolus vulgaris) is said to interfere with the breakdown and absorption of carbohydrates.

To date, few clinical trials have examined white kidney bean extract's effects on weight. Reported side effects include loose stools, gas, constipation, and headache.

Bitter Orange

In recent years, bitter orange (Citrus aurantium) has been marketed as a natural weight loss aid. Proponents claim that the substance (which contains synephrine, a stimulant related to the main compound in the banned herb ephedra) can stimulate caloric burn, but very little research exists to fully support this claim.

According to the National Center for Complementary and Integrative Health, there isn't enough evidence to support the use of bitter orange.

Bitter orange has also been associated with some serious adverse effects, including chest pain, increased blood pressure and heart rate, and anxiety.

There are also reports that bitter orange may have harmful side effects when taken alone or with stimulants (including caffeine), medications, and other supplements.

Possible Side Effects

While natural supplements may appear safe, the way weight loss supplements work means they may pose greater risks than the average supplement.

For example, some supplements are stimulants, while others are laxatives. It's also possible for any type of supplement to be contaminated with banned substances or another potentially harmful ingredient.

Adverse events often go unreported because there is a lack of scientific research and reporting, making it impossible to know the full range of possible side effects and adverse events.

Like many dietary supplements, these weight loss supplements have not been thoroughly tested for safety in pregnant women, nursing mothers, children, those with medical conditions, or people taking medications.

The Bottom Line

Supplements may seem like an appealing alternative to exercise and changing your diet if you want to lose weight, but limited evidence and safety concerns mean it's still too soon to recommend any of these supplements for weight loss.

If you're still considering taking a weight loss supplement as part of a healthy diet and exercise plan, talk to your healthcare provider first to weigh the pros and cons.

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