How Does Glucomannan Help You Lose Weight?

How Does Glucomannan Help You Lose Weight?

The key to weight loss is to have a good diet and exercise regularly. But if it was that easy we wouldn’t be in the midst of an obesity epidemic. The truth is, losing weight can be hard.

It requires motivation and determination, and with so many obstacles in the way you need to consider any extra help you can get.

There are a number of nutrients that will support your weight loss program. Some are better than others though, so you need to make sure you’re getting the best and that you take your time to research each one fully.

In this article we’ll take a look at glucommanan and how it can support your weight loss goals.

What is Glucomannan?

Glucommanan is a natural product of the konjac plant. Otherwise known as amorphophallus konjac or more commonly the elephant yam, it is a plant native to tropical eastern Asia. Dark purple in color, konjac is a single leaf perennial which provides a water soluble dietary fiber and source of sugar in traditional eating.

Konjac is very low in calories but high in soluble fiber, with glucommanan making up around 40% of the plant root. It has a long-chain, complex structure that consists of a polysaccharide chain of beta-D-glucose and beta-D-mannose.

Put simply, it is a complex carbohydrate source that takes time to break down in the gut. Because of the arrangement of sugars, human saliva finds it hard to break it down. This means it passes into the gut largely in tact, where it is at that point fermented by gut bacteria. The fermentation and digesting process then gives you a feeling of fullness for a much longer period than with other foods.

Additionally, glucomannan has a high molecular weight and can absorb up to 50 times its weight in water, which also boosts its appetite suppressing effects. It is used widely in East Asian cuisine – being a popular ingredient in pasta, noodles, flour and soup. It has no taste, but has a gel-like texture that is similar to fruit pectin or guar gum.

Food that is rich in fiber has been associated with lower metabolic disease risk. Not only do they lower the risk of cardiovascular disease, they also benefit other illness too – diabetes and hypercholesterolemia for example.

As a source of fiber, glucommanan has been used clinically to treat a number of health conditions including constipation, type 2 diabetes and regulating both blood sugar and cholesterol.

It has also been used widely in both adults and children as a weight loss nutrient.

How Does Glucommanan Boost Weight Loss?

Any successful weight loss or fat loss plan has to include a calorie deficit that puts you into a negative energy. By taking in less calories than you burn off your body begins to use excess fat stores as fuel, leading to fat loss.

The problem is though that when you exercise on a regular basis you often feel hungry – and this can make eating less much harder. You often work hard in the gym, but overcompensate by eating far more than you should.

There are 4 main benefits that glucommanan provides for weight loss are:

  • Decreases appetite
  • Absorbs water
  • Improves blood sugar and lipid profile
  • Improves gut health

According to one study, glucommanan seems to promote weight loss by displacing the energy of other nutrients and producing satiety and satiation as it absorbs water and expands in the gastrointestinal tract [1].

Fiber supplements in general have been shown to aid in short-term weight loss in a number of studies [2, 3].

Because it is high in soluble fiber, this nutrient becomes viscous when it comes into contact with fluids. Its then takes on a gel-like consistency in the gut and expands to give a feeling of fullness. This is useful for anyone wanting to decrease food intake during periods of intense physical activity. 

Studies have backed this up too. For example, Birketvedt et al [4] found that when the konjac nutrient was including in a calorie-restricted diet, participants lost significantly more weight.

A high-quality, double-blind study of obese subjects also found that glucommanan led to weight loss [5]. The research team gave participants two 500mg capsules and 8 oz of water 1-hour prior to each of tree meals per day over an 8-week period.

Each subject was instructed not to change the way they ate, nor to restrict or necessarily include exercise. The results found that not only did their cholesterol decrease, they lost a significantly higher amount of weight too. This is great for those who don’t want to follow a very restricted plan.

A similar conclusion was also seen in a large-scale critical review – a type of research that critically discusses studies in detail. In the study, researchers stated clearly that glucommanan resulted in significant weight loss and could help to decrease the high prevalence of overweight and obesity in the United States [6].

Lastly, a robust systematic review (often cited as being one of the most rigorous types of research) found that when 6 controlled studies were independently analyzed, short-term weight loss was observed [7]. Although no changes to body mass index were seen across all studies, body weight had clearly decreased.

It is quite clear then that if you wish to lose weight or body fat, glucommanan can help you. In combination with a calorie-controlled diet, the supplement will help you lose weight not just long-term, but short-term too.

Is Glucommanan Safe?

Yes, very safe. As it is approved to be used in the commercial food industry, glucomannan foods are likely safe when consumed by both adults and children.

One study that looked directly at safety outcomes found that glucomannan was safe, well tolerated, and had no adverse side effects [1]. Both liver and kidney function was normal throughout supplement use, and did not differ to a control group. There was a slight increase in belching, but that was only on an occasional basis and lasted only for the first three days  of the study.

In supplement form, it should always be taken as directed by manufacturers. Due to it expanding so quickly it should not be taken as a dry powder other than in pill form. You should also not exceed the stated dose due to its ability to swell and expand.


Glucomannan comes from the konjac plant, or elephant yam. It is low in calories but provides a complex carbohydrate source that is high in soluble fiber.

It has been used in clinical settings to reduce the risk of cardiovascular disease, high cholesterol and diabetes. It has also been used in obesity studies too.

Clinical trials show that adding glucomannan to the diet can aid in weight loss primarily by reducing appetite. When combined with a calorie restricted diet, this supplement can accelerate your results and help you achieve your goals.


  1. Keithley, JK et al. Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults. J Obes. 2013
  2. Krotkiewski, M. Effect of guar gum on body-weight, hunger ratings and metabolism in obese subjects. Br J Nutr. 1984; 52(1): 97–105
  3. Pittler, MH et al. Guar gum for body weight reduction: meta-analysis of randomized trials. Am J Med. 2001; 110(9): 724–30 13
  4. Birketvedt, GS et al. Experiences with three different fiber supplements in weight reduction. Med Sci Monit. 2005; 11(1)
  5. Walsh, DE et al. Effect of glucomannan on obese patients: a clinical study. Int J Obes. 1984; 8(4): 289-93
  6. Keithley, J et al. Glucommanan and obesity: a critical review. Altern Ther Health Med. 2005; 11(6): 30-4
  7. Zalewski, BM et al. The effect of glucomannan on body weight in overweight or obese children and adults: a systematic review of randomized controlled trials. Nutrition. 2015; 31(3): 437-42