Glucomannan: Can It Truly Aid Weight Loss?

With new weight-loss supplements emerging on the market all the time, it can be difficult to know which ones will do the work and which ones won’t do you any favors.

Too many people struggle with the concept of dieting when it comes to losing fat and staying lean.

That’s why we’re taking a closer look at Glucomannan, a water-soluble fiber supplement that’s been dubbed one of the best ways to control your hunger. It does this by hampering appetite[1], therefore reducing the amount of food you eat.  

The question is – does it actually work? Can Glucomannan aid weight loss?

In this article, we’ll examine the science behind Glucomannan, its side effects and if it has the potential to aid and manage weight loss.

What is Glucomannan?

Glucomannan is a water-soluble fiber supplement made from the root of the konjac plant. You may also know it as konjac, konjaku, snake palm or elephant yam.

Native to the people of East Asia, it has been used as a food additive and emulsifier and in traditional medicine for centuries.

Nowadays, more people purchase Glucomannan in supplement form rather than its natural form. It is available in powder form, tablets or even in food products such as Japanese shirataki noodles.

Like other fibers, Glucomannan can help you feel more satisfied after a meal – what makes it so unique is its water absorption capability.

Being one of the most viscous of all known dietary fiber, Glucomannan has the ability to absorb 50 times its weight in water [1]. It is so viscous that if you were to empty one Glucomannan capsule into a glass, the entire glass would form a thick gel. 

How does Glucomannan work?

Glucomannan has an excellent ability to absorb water.

When consumed, Glucomannan creates a feeling of fullness in the stomach (satiety), by absorbing water and expanding to form a gel-like mass. These unique properties are thought to mediate its ability to support weight loss.

Glucomannan is believed to provoke fat loss by acting as a bulking agent, increasing satiety and reducing caloric intake as well as ingestion rate[2].

It may also decrease the amount of the hunger hormone ghrelin[3] in your body.

Is Glucomannan safe?

Glucomannan has been recognized as safe by the FDA since 1994[4] and appears to be well tolerated for short-term use.

How can Glucomannan aid weight loss?

Glucomannan has been studied extensively for its effect on weight reduction.

It is extremely low in calories but high in fiber – manufacturers say a typical powder serving of 1.5 grams contains 0.45 calories and 1.3 grams of fiber[5]. Its mechanism of action is believed to promote and maintain weight loss in a number of ways:

  • It fills space in your stomach to promote a feeling of fullness and subsequently reduce the amount of food you eat[6]
  • It delays stomach emptying so that you feel fuller for longer[7]
  • It reduces the amount of protein and fat absorbed by your body[8]
  • It may help break down carbohydrates more slowly, stabilizing blood sugar levels

In one study, Glucomannan as a food supplement was given to obese adults one hour prior to each three meals per day. Participants did not change their eating or exercising patterns and by the end of the study, they had lost 5.5 pounds over an eight-week period[9].

Dosing considerations

Ideally, you should aim to consume 30 to 50 grams of fiber day-to-day, which should be a mix of soluble and insoluble fibers.

A dose of around two to four grams of Glucomannan has been shown to be safe in studies and is usually well tolerated – this amount has shown to result in significant weight loss in individuals who are overweight when used alongside a calorie-restricted diet.[10]

A Glucomannan supplement should be taken 30-60 minutes before a meal and always consumed with enough water (at least one glass) – this is down to its ability to absorb moisture.

Without enough water, Glucomannan could fail to offer the health benefits you’re looking for and cause serious side effects.

Woman drinking water

Glucomannan: other health benefits

Apart from helping you maintain your weight, there are other health benefits associated with Glucomannan. These include:

  • Lowered cholesterol

Having high cholesterol makes you more prone to heart disease or the risk of a stroke.

Glucomannan may help you keep cholesterol levels in check because of its ability to decrease the absorption of cholesterol in the gut – a study discovered that Glucomannan was able to lower total cholesterol by 19.28mg/dL and harmful LDL cholesterol by 15.99 mg/dL[11]

Another study suggested that large volumes of cholesterol are excreted when Glucomannan is consumed – it enhanced fecal excretion and bile acids, decreasing intestinal absorption of cholesterol[12].

  • Reduced blood sugar levels

About 422 million people worldwide suffer with diabetes[13] – a serious condition which can lead to damage to the kidneys, heart, eyes and blood vessels. Yet diabetes is a preventable disease in many cases.

Diabetes sufferers may want to pay more attention to Glucomannan and how it may improve blood sugar levels.

It may improve lipid profile and delay stomach emptying, leading to more gradual sugar absorption and potentially lowering glucose levels to recommended levels[14]

A study from 2015 also noted that Glucomannan stopped diabetics from eating foods which could increase their blood sugar levels, simply because it made them feel fuller for longer[15].

  • Better gut health

Glucomannan may contribute to good gut health. As a viscous dietary fiber, it is a bonus for certain friendly bacteria which reside in our gut, otherwise known as probiotics.

Glucomannan is a water-soluble fiber which is great food for gut bacteria, earning itself the term prebiotic. Glucomannan is considered a prebiotic because it passes through the upper part of the digestive tract and cannot be digested.

Once Glucomannan reaches the colon it is eagerly fermented by gut bacteria into friendly probiotics and beneficial short-chain fatty acids (SCFAs)[16].

SCFAs are the main source of energy for the cells that line your colon. They play an important role in the maintenance of health and the development of disease[17] and may promote weight loss by protecting against diet-induced obesity, reducing appetite and energy intake[18].

Gut health
  • Constipation relief

The average adult is believed to consume less than 20g of dietary fiber a day – the recommended intake is around 30g a day. A low-fiber diet is associated with constipation as well as other gut diseases[19].

Being a non-digestible fiber, Glucomannan could be effective against chronic constipation[20].

This means it works by building bulk in our intestines and ‘speeding up’ food transit time through the colon[21], as well as increasing regularity.

In one study, Glucomannan improved bowel movements in adults by 30 per cent as well as their colonic ecology – increasing the concentration of beneficial gut bacteria such as bifidobacteria[22].

Glucomannan: the side effects

Like all supplements, you should be vigilant with the use of Glucomannan and keep in mind the side effects associated with the ingredient.

Because it is a natural ingredient, Glucomannan contains zero additives or chemicals so it is generally considered safe when consumed within the recommended guidelines.

Still, there are some interactions and side effects to be aware of:

  • Risk of choking

When taking Glucomannan supplements, the number-one thing to think about is the amount of water you drink.

In extremely rare cases, Glucomannan can cause choking by obstructing your throat, because of its high viscosity[23].

Taking Glucomannan supplements with a generous amount of water will prevent this risk – around one to two glasses of water should do the trick. Don’t take Glucomannan if you have any intestinal blockages.

  • Abdominal discomfort

As a fiber, Glucomannan can cause gastrointestinal discomfort – especially if you suddenly increase the amount of fiber you consume.

This discomfort can be anything from flatulence, bloating and loose stools to stomach pains and belching. Glucomannan must be introduced to your diet over time to mitigate the risk of any abdominal side effects.

  • Drug interaction

Glucomannan may reduce the absorption of certain medications, including anti-diabetic or anti-cholesterol drugs. If you are on these drugs and intend to use Glucomannan, you should speak to your doctor or a healthcare professional first.

Glucomannan may interact with medication
  • Allergic reactions

If you have symptoms such as difficulty breathing, itchy skin or a rapid heart rate, stop taking Glucomannan and get medical help.

Something to consider: Glucomannan risks and precautions

Glucomannan may interfere with blood sugar control – if you are diabetic and considering taking Glucomannan, closely monitor your glucose levels or consult with your doctor first.

The supplement should be avoided by anyone who is allergic to Glucomannan-containing products or individuals who cannot handle its bloating effect. 

There is not enough reliable research about the safety of Glucomannan on pregnancy or breastfeeding. So to err on the side of caution, stay on the safe side and avoid use.   

The Final Word  

Glucomannan appears to have all the science behind it showing it can support health conditions such as obesity, cholesterol and diabetes.

After a close look at the evidence, is the fiber worth adding Glucomannan to your supplement list?

Like any other weight-loss tactic, adding Glucomannan to your diet is only one part of the puzzle. To lose weight, you must make a permanent change to your nutrition and follow a healthy lifestyle – Glucomannan may just give you that health boost you need.

If you’re on the fence about its supplement form, why not try Japanese shirataki noodles – also known as the ‘zero-calorie miracle noodles’?

They’re made from Glucomannan, low in calories and are extremely filling due to their fiber content. They also offer a simple way to try Glucomannan.







[6] As source 1


















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