Glucomannan and Weight Loss: The Facts

Medically approved by
Dr Earim Chaudry
Last updated
3rd February 2022

In 30 seconds

Glucomannan is a dietary fibre that comes from elephant yam, the root of the konjac plant. It is often sold as a dietary supplement thanks to its possible health benefits, including lowering cholesterol and regulating blood sugar levels. But what’s the link between glucomannan and weight loss? Evidence suggests this fibre can help suppress appetite, promote feelings of fullness, and reduce calorie consumption. However, it will only help as part of a balanced diet and active lifestyle.

Finding the Right Weight Loss Method for You

With so many products out there claiming to help you lose weight, it’s not always easy to know what to trust – and it can be pretty hard to find reliable information.

We understand the struggle. That’s why we’re working to share objective, science-backed information about the best health solutions.

In this article, we want to talk about glucomannan and weight loss. Glucomannan is a dietary fibre promoted as a health supplement to support weight loss, lower cholesterol, and treat constipation. You can find out more about the benefits of glucomannan here. 

But does glucomannan work for weight loss? Here’s what we know so far.

What is Glucomannan?

Glucomannan is a dietary fibre that comes from elephant yam, the root of the plant known as konjac that grows in South Asia. It has been long used as an additive in foods including pasta and sweets – as a thickener, emulsifier, and binding agent. But it’s now being promoted as a health supplement – and particularly as a weight loss supplement.

Why? Glucomannan boasts remarkable properties as a viscous fibre. For example, it can absorb up to 50 times its weight in water. That means it may be particularly effective as a fibre, with all the benefits that fibres bring.

So, does it work?

How Fibre Helps Weight Loss

Like other fibres, glucomannan may help bodyweight management in several ways. Let’s take them one by one.

  • Fibre supports a healthy gut: Prebiotics are a type of dietary fibre that acts as a fuel for the good bacteria in your gut. These gut bacteria help keep your digestive tract in good health. When they’re well-balanced, they’ve been found to support weight loss plans by reducing appetite and slowing the absorption of dietary fats.

Glucomannan supplements have been found to help create a balanced gut.

  • Glucomannan can help you feel full: Foods rich in fibre are known to increase feelings of fullness and satiety and to act as an appetite suppressant. As a potent fibre, glucomannan is known to do precisely this. However, it’s not clear whether glucomannan helps reduce appetite more than any other fibre.
  • As a result, fibre reduces calorie consumption: People who eat a lot of fibre have been found to eat fewer calories overall thanks to its appetite-reducing effects. With a lower food intake, weight loss may be more manageable.
  • It slows stomach emptying: Alongside reducing appetite, glucomannan is known to slow down the process of gastric emptying. This has been found to help weight loss.

Taking Glucomannan for Weight Loss: Does it Work?

So, does glucomannan work for weight loss? The evidence so far shows the results are mixed, but there is good reason to be hopeful.

  • One study compared three different dietary fibres for their effect on weight loss in overweight adults. Fibre supplements were given to 176 people alongside a low-calorie controlled diet (1,200 calories a day). All of the adults showed significant weight loss after 5 weeks. However, the study did not find that glucomannan was particularly effective compared to the other fibres included.
  • Another study involved giving adults 1.3 grams of glucomannan powder before breakfast, lunch, and dinner. After 8 weeks, it did not find any difference between weight loss results in those that took glucomannan and those that took a placebo.
  • However, two other studies did find evidence that glucomannan can help with weight loss. In one study, 20 obese subjects were given 1 gram of glucomannan before meals, and on average, they lost 5.5 pounds over eight weeks. A systematic review found that glucomannan can reduce appetite, which can help weight loss.

The results are, ultimately, inconclusive. There is hope that glucomannan can be an effective weight loss solution, but there’s not enough evidence to say for sure. 

However, what seems to be clear is that glucomannan is effective only when taken as part of a healthy balanced lifestyle. That means a diet with enough proteins, complex carbohydrates, and fruit and vegetables, alongside regular physical activity and sound sleep.

You can find out all you need to know about weight loss strategies for men here: Weight Loss Plans for Men: Options and Tips

What are the Side Effects of Glucomannan?

Glucomannan may positively impact weight loss, but is it safe? Let’s take a look at the side effects to watch out for when taking the food supplement:

  • It may be a choking hazard: Some glucomannan products are banned in Australia and the EU because they have been found to pose a risk of choking. In some cases, the glucomannan powder has expanded in people’s throats before reaching their stomachs. 

Taking glucomannan with a couple of small glasses of water will help you bypass this risk.

  • It can give you diarrhoea: Glucomannan is a ‘bulk-forming laxative’ that is often used as a treatment for constipation. However, take too much of the soluble fibre, and it can be too effective.
  • Glucomannan can cause bloating: A common complaint of people who start to take glucomannan is that it causes bloating and flatulence. This is normal. It’s a common consequence of introducing lots of fibre into your diet. 

Key Takeaways

Glucomannan can be an effective tool in your weight loss plan. It can reduce your appetite, promote a balanced gut, and ease constipation — and this can help you achieve a healthy weight and feel healthier overall. 

But glucomannan will have its most significant effects when taken as part of a healthy lifestyle. Combining the fibre with regular physical activity, good sleep, and a balanced diet is most likely to bring results.


Is Glucomannan Safe?

Glucomannan has regularly been shown to be safe and effective. But it is recommended that you stick to small doses and ensure that you take it with lots of drinking water.

This should help you avoid any possible nasty side effects, such as choking or diarrhoea.

Is It Safe to Take Glucomannan with Other Medications?

It is safe to take glucomannan even if you are on other medications. 

However, given that glucomannan is such a viscous fibre, it’s recommended that you do not take your medication at the same time as you take your glucomannan supplement. This can affect the way that the medicine is absorbed.

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Further reading

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