What are the health and weight-loss benefits of konjac?

What is konjac?

Konjac (Amorphophallus konjac) is a perennial plant native to South-East Asia. It has been used for centuries in traditional Japanese and Chinese medicine.

Its rhizome, or root, contains a soluble fibre with exceptional water-retaining properties: glucomannan.

Now very popular in the slimming world, this food comes in several forms:

• dietary supplements (capsules or powder)
• konjac vermicelli and noodles (called shirataki) for cooking
• konjac rice for cooking
• konjac flour for recipes
• blocks to be cut up to meet different needs

If you want to add konjac to your diet, make sure you never eat it raw. Uncooked konjac contains potentially toxic calcium oxalate crystals (1). However, this precaution does not apply to the powder, which is dried before packaging.

The main benefits of konjac

Konjac: a weight loss ally

Konjac is best known for helping dieters lose weight.

Studies have looked at the effects of the glucomannan fibres it contains. These fibres are capable of absorbing the equivalent of several times their weight in water.

Once loaded with water, they form a viscous gel. When ingested with liquids during a meal, they take up space in the stomach, making you feel fuller and providing a natural appetite suppressant (2).

Glucomannan consumed as part of a low-calorie diet is therefore thought to contribute to weight loss.

What's more, in addition to its high fibre content, konjac is low in calories (10 to 20 kcal/100g) and has an unobtrusive taste, so it can be combined with a variety of condiments, sauces and foods.

This is why it is so popular with many people on restrictive diets, as it helps to maintain the pleasure of eating through varied recipes.

Aids intestinal transit

Thanks to its high fibre content, konjac has been studied for its potential effects on intestinal transit.

By swelling on contact with water, the glucomannan in konjac helps to increase the volume of stools in the intestine and improve their consistency.

Research suggests that this fibre may relieve episodes of mild and occasional constipation (3).

Potential beneficial effects on cholesterol levels

Scientific research suggests that eating konjac may have an impact on lipid metabolism. The glucomannan it contains helps maintain normal blood cholesterol levels.

According to some studies, this fibre is capable of trapping some of the fats provided by food, particularly cholesterol, thereby limiting its absorption during digestion (4).

Possible support for blood sugar regulation

Some clinical studies suggest that konjac may help to modulate postprandial glycaemic response (measured after a meal).

The gel formed by the glucomannan in the digestive system is thought to slow the absorption of carbohydrates from the diet.

This limits blood sugar peaks after meals, and also limits insulin secretion from the pancreas, a mechanism that is disrupted in people suffering from diabetes (5).

What to look out for when eating konjac

While the potential benefits of konjac are interesting, it is important to be aware of certain points concerning it and to use it with caution.

As a food, konjac has a very low nutritional density. It contains virtually no vitamins, minerals or proteins.

It cannot therefore be used as a substitute for a balanced meal, but only as a supplement, to increase its volume without increasing the calorie intake.

Additionally, for people who are not used to eating fibre, it can cause temporary digestive problems such as bloating and flatulence.

What's more, certain forms of konjac (jellies and jelly beans) have been banned in several countries, due to the risk of choking.

The most common and safest formats today are still food supplements, konjac rice and konjac noodles.

Finally, take particular care if you are taking medication. The high absorption capacity of konjac fibre could affect the absorption of some medicines.

A key ingredient in slimming food supplements

Thanks to its high soluble fibre content and ability to swell in the stomach (with few contraindications), konjac has become an essential slimming ingredient.

It is often combined with other active ingredients to act synergistically on weight management or metabolism, as part of a healthy lifestyle.

Some formulas, for example, combine glucomannan, which contributes to weight loss as part of a low-calorie diet, with amino acids involved in energy production, or with plant extracts (green coffee, green tea, guarana, etc.).

Other types of active ingredients can also be selected for their various benefits.

If you're looking to take advantage of the benefits of konjac combined with other active ingredients, you can turn to a dietary supplement containing an extract.

• Discover Weight Loss Formula, which contains propolmannan, a natural, purified and patented dietary fibre derived from konjac.