The Scoop on Natural Weight Loss Supplements

Can They Help or Harm?

Green tea in two japanese ceramic cups
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In order for weight loss to be sustainable, it has to be something you can realistically keep up. Given the time and effort that goes into exercising and changing the way you eat, natural supplements can seem like an appealing way to slim down.

Diet supplements, however, aren’t regulated and most of them have little evidence backing up their claims. What's more, weight loss supplements have been found to contain banned ingredients (such as ephedra) and some of them have been associated with serious adverse events like liver injury. Here's what you need to know about some of the most common ingredients.

1) Apple Cider Vinegar

Although there is limited evidence suggesting that the apple cider vinegar component acetic acid (found in many other types of vinegar) may help to suppress your appetite, there's no evidence that taking apple cider vinegar supplements can help you lose weight.

Using apple cider vinegar in normal amounts in cooking shouldn't pose a problem for most people, however, there's concern that undiluted apple cider in larger amounts (in pill or liquid form) can injure the esophagus and other parts of the digestive tract.

2) Chitosan

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 it can block fat absorption, there's little scientific support that it can help with weight loss.

Chitosan may cause allergic reactions if you have a shellfish allergy, and it has been known to cause adverse events such as bloating, gas, constipation, indigestion, heartburn, and nausea.

3) 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 claim that CLA may decrease fat while building muscle, research results have yielded mixed results. Possible side effects include abdominal discomfort, constipation, nausea, and loose stools, and some sources caution against long-term use due to adverse effects on blood lipids and glucose.

4) Fucoxanthin

Fucoxanthin is an antioxidant found naturally in edible brown seaweed such as 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 trials testing the effects of fucoxanthin (and the safety) are currently lacking.

5) Glucomannan

A soluble fiber-rich substance extracted from the root of the konjac plant, glucomannan has gained popularity as a weight loss aid. According to proponents, glucomannan 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 blockage in your digestive tract.

6) Green Tea

There is some research indicating that substances in green tea, such as theanine, may raise your metabolism and curb your appetite, but overall the research findings have been mixed. Although taking a green tea supplement may not help you with weight loss (and the caffeine content may be a problem for some), drinking green tea may support your efforts if it's part of a healthy eating plan.

7) Hoodia

A cactus that grows in the Kalahari desert in Africa, hoodia 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. And fake hoodia is a problem (it has been estimated that more than half of all hoodia products are not the real thing). Adverse effects have included headache, nausea, vomiting, and dizziness, and there's some concern that it may raise blood pressure and heart rate.

8) Raspberry Ketones

The chemicals that give red raspberries their sweet scent, raspberry ketones are 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 research suggests that the substance may offer some anti-obesity benefits, there's no solid evidence that it can support weight loss in humans. What's more, there's some concern that the use of raspberry ketones may stimulate the release of norepinephrine and be harmful for people with certain conditions.

9) 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. Some of the side effects that have been reported include loose stools, gas, constipation, and headache.

10) Bitter Orange

In recent years, bitter orange (Citrus aurantium) has been marketed as a natural aid. Proponents claim that the substance (which contains synephrine, a stimulant related to the main compound in the banned herb ephedra) can help stimulate the number of calories burned.

According to the National Center for Complementary and Integrative Health, there isn't enough evidence to support the use of bitter orange. What's more, the use of the supplement has been associated with chest pain, increased blood pressure and heart rate, and anxiety and there are reports that they may have resulted in harmful side effects in people who took bitter orange alone or combined with stimulants (such as caffeine), medications, and supplements.

Possible Side Effects

While natural supplements may appear safe, weight loss supplements can pose greater risks than the average supplement, because of the way that they work. Some are stimulants, while others are laxatives. Contamination of supplements with banned substances and other potentially harmful ingredients is also possible. Due to a lack of reporting, adverse events often go unreported, making it impossible to know the full range of possible side effects and adverse events.

None of these supplements have been tested for safety in pregnant women, nursing mothers, children, and those with medical conditions or who are taking medications. Get tips on using supplements safely.

The Bottom Line

Although supplements may seem like an appealing alternative, It's too soon to recommend any supplement for weight loss due to the limited evidence and safety concerns. If you're still considering trying them, be sure to speak with your healthcare provider first to weigh the pros and cons.

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Article Sources
  • Ni Mhurchu C, Dunshea-Mooij CA, Bennett D, Rodgers A. Chitosan for overweight or obesity. Cochrane Database Syst Rev. 2005 Jul 20;(3):CD003892.
  • Whigham LD, Watras AC, Schoeller DA. Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans. Am J Clin Nutr. (2007) 85.5: 1203-1211.