Glucomannan for Fat Loss – Is It Any Good?

Konjac Root glucomannanGlucomannan is a type of dietary fibre that originated from the root of the konjac plant. Studies are increasingly revealing the many benefits that this fibre offers, with it having numerous health benefits as well as aiding weight loss. Studies show that glucomannan induces weight loss, by suppressing appetite and reducing absorption of fat from the small intestine.

Overweight and obesity are a proven risk for conditions such as diabetes and cardiovascular diseases (National Task Force on the Prevention and Treatment of Obesity, 1996). Advice on how best to lose weight, and keep it off, has changed over the years as research has revealed more about how our bodies work.

However, dieting and exercising to lose weight (and finding a method to suit you) can be a struggle and feel like an up-hill battle. The use of weight loss supplements containing natural ingredients has gained popularity as a means to make losing weight easier, to the point where the herbal weight loss supplements market is worth billions globally.

Ingestion of dietary fibre has always been recommended by dieticians and doctors for maintaining intestinal health and digestive regularity; eating too little fibre is the most common cause of constipation, and studies show that eating a diet high in fibre reduces your risk of bowel cancers and other illnesses.

What is Glucomanan?

There is also significant evidence to show that increasing your fibre intake in general can help to regulate your weight. Fibre is indigestible, and so does not add calories to your food, but does take up space in your stomach, helping to regulate the appetite. Several studies have looked specifically at the absorption properties of dietary fibre; it seems that when fibre absorbs water in the digestive system, it also binds with a small amount of food, preventing it from being fully digested.

Not all fibres are created equally; glucomannan is one of the most absorbent types of fibre, which appears to play a role in why it works to suppress the appetite and aid weight loss more than other types of fibre. Estimates of how much water glucomannan can absorb vary, but in test tube conditions a single gram of glucomannan can absorb around 100 ml of water (Walsh et al., 1984), thickening it into a gel similar in looks to wallpaper paste. Another estimate states that it can absorb up to 50 times its weight in water, making it one of the most viscous dietary fibers known.

Glucomannan is derived from the roots of the Konjac plant which is indigenous to East Asia. Human beings have used glucomannan since time immemorial, knowing fully well its abilities to cleanse the intestines. It has been used in Japanese cuisine for more than a 1000 years (Walsh, Yaghoubian, & Behforooz, 1984). Konjac Fibre is now much more widely available in the USA and Europe than even a few years ago. It is the main ingredient Shirataki Noodles, which are sometimes marketed as zero calorie noodles.

It is a soluble fibre, meaning that it can readily absorb water, and will ferment in the digestive tract somewhat, but ultimately it remains indigestible by the body, and passes through the digestive tract and is excreted.

Glucomannan consumption can aid weight loss in numerous ways, but the two predominant ways are through appetite suppression and reduction of food absorption.

  • Appetite Reduction: Glucomannan fibre swells as it absorbs water, helping to fill the stomach without increasing the calorific value of a meal and making you feel full quicker. The thick gel then slows the emptying of the stomach, delaying the onset of hunger after a meal further.
  • Reduction of absorption of fats and carbohydrates: As the glucomannan fibre absorbs water and swells, the gel forms around food particles, capturing them and reducing the amount of food that is fully digested. This effectively reduces the calorific value of meals.

Other Health Benefits of Glucomannan Supplementation

Regular ingestion of glucomannan affords a list of other health benefits as well:

  1. Reduces rate of absorption of sugar – this translates to better sugar control (useful for people with type 2 diabetes or pre-diabetes) and prevents insulin spikes which translates into sugar crashes and cravings
  2. Enhances insulin sensitivity and regulates blood glucose levels (Chen, Sheu, Tai, Liaw, & Chen, 2003) – helpful to treat insulin resistance
  3. Reduces cholesterol levels significantly (Anderson et al., 2009; Kreider et al., 2010; Gallaher et al., 2002; Gallaher, Munion, Hesslink, Jr., Wise, & Gallaher, 2000)
  4. Prevents occurrence of constipation, and reduces bloating and indigestion (Walsh et al., 1984)
  5. Reduces risk of cancer of large bowel in the longer run

Thus, not only does glucomannan reduce your body weight (Anderson et al., 2009) but also keeps your digestive and cardiovascular systems in great shape. Furthermore, it seems to lend an effective treatment support in diabetes as well.

The general health benefits of glucomannan can be summarized as follows:

  • Better regulation of blood sugar levels
  • Enhanced insulin sensitivity
  • Significant reduction in blood cholesterol
  • Prevention of constipation
  • Reduces risk of developing bowel cancer

Is it Safe To Consume Glucomannan?

Glucomannan is generally considered safe for consumption. When taken properly (with adequate water especially), potential side effects are not serious. Because it is a fibre, you can expect a slight increase in the number or size of bowel movements. Typically any digestive side effects that are experienced in the first few days of use fade over time, as the body gets used to the increased high-fibre diet.

There is some risk of choking due to glucomannan’s ability to absorb water and swell up so much. However, when the fibre is in capsule form, and is taken with plenty of water, the risk of choking or Oesophageal obstruction is greatly reduced.

What Does The Research Say?

Glucomannan for Fat Loss – ResearchAlthough not all of the available clinical trials are 100% in agreement, Glucomannan’s benefits have been recognised by the European Food Safety Authority (EFSA); they have approved Glucomannan as an appetite suppressant and weight loss aid, providing that the daily serving consists of three doses of a gram each.

This is based upon an analysis of the available clinical research into the fibre and its benefits.

Vasques et al (2008) argued that glucomannan did not aid weight loss, but they studied its use in conjunction with another common diet pill ingredient, Garcinia Cambogia.

A meta-analysis of fourteen studies published prior to 2007 found that glucomannan “significantly lowered total cholesterol, LDL cholesterol, triglycerides, body weight and fasting blood glucose levels” (Sood et al. 2008). As this meta-analysis combines the results of 14 comparable studies, it has a large number of participants whose results are analysed (531 people in total). Larger studies are generally better, as they offer more accuracy in their results.

The glucomannan-taking participants in Walsh et al’s study (1984) lost an average of 5.5lbs over an 8 week period, something not witnessed in the placebo group.

Whilst the available studies that have looked at Glucomannan and its relationship to weight loss are not 100% in agreement, generally they do point towards the idea that Glucomannan does aid weight loss, especially in conjunction with other weight loss measures. In at least one study where the placebo group and glucomannan group’s weight changes were similar to each other, neither group were trying to lose weight. As glucomannan acts as an appetite suppressant, it might be useful for supporting an existing diet plan by reducing hunger (and helping the dieter to stick to the diet plan). We encourage people to think of Glucomannan as a weight loss tool rather than a method of weight loss by itself.


  • Walsh, D. E., Yaghoubian, V., & Behforooz, A. (1984). Effect of glucomannan on obese patients: a clinical study. Int J Obes, 8, 289-293.
  • Sood N, Baker WL, Coleman CI. 2008. Effect of glucomannan on plasma lipid and glucose concentrations, body weight, and blood pressure: systematic review and meta-analysis. Am J Clin Nutr. 2008 Oct; 88(4):1167-75.
  • Joyce K. Keithley, Barbara Swanson, Susan L. Mikolaitis, Mark DeMeo, Janice M. Zeller, Lou Fogg, and Jehan Adamji, Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults. J Obes. 2013; 2013: 610908.
  • Anderson, J. W., Baird, P., Davis, R. H., Jr., Ferreri, S., Knudtson, M., Koraym, A. et al. (2009). Health benefits of dietary fiber. Nutr.Rev, 67, 188-205.
  • Chen, H. L., Sheu, W. H., Tai, T. S., Liaw, Y. P., & Chen, Y. C. (2003). Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects-a randomized double-blind trial. J Am Coll.Nutr., 22, 36-42.
  • Gallaher, C. M., Munion, J., Hesslink, R., Jr., Wise, J., & Gallaher, D. D. (2000). Cholesterol reduction by glucomannan and chitosan is mediated by changes in cholesterol absorption and bile acid and fat excretion in rats. J Nutr., 130, 2753-2759.
  • Gallaher, D. D., Gallaher, C. M., Mahrt, G. J., Carr, T. P., Hollingshead, C. H., Hesslink, R., Jr. et al. (2002). A glucomannan and chitosan fiber supplement decreases plasma cholesterol and increases cholesterol excretion in overweight normocholesterolemic humans. J Am Coll.Nutr., 21, 428-433.
  • Gonzalez, A., Fernandez, N., Sahagun, A., Garcia, J. J., Diez, M. J., Castro, L. J. et al. (2004). Effect of glucomannan and the dosage form on ethinylestradiol oral absorption in rabbits. Contraception, 70, 423-427.
  • Henry, D. A., Mitchell, A. S., Aylward, J., Fung, M. T., McEwen, J., & Rohan, A. (1986). Glucomannan and risk of oesophageal obstruction. Br.Med J (Clin Res.Ed), 292, 591-592.
  • Kreider, R., Wilborn, C., Taylor, L., Campbell, B., Almada, A., Collins, R. et al. (2010). ISSN exercise & sport nutrition review: research & recommendations. Journal of the International Society of Sports Nutrition, 7, 7.
  • National Task Force on the Prevention and Treatment of Obesity (1996). Long-term pharmacotherapy in the management of obesity: National task force on the prevention and treatment of obesity. JAMA, 276, 1907-1915.
  • Vasques, C. A., Rossetto, S., Halmenschlager, G., Linden, R., Heckler, E., Fernandez, M. S. et al. (2008). Evaluation of the pharmacotherapeutic efficacy of Garcinia cambogia plus Amorphophallus konjac for the treatment of obesity. Phytother.Res., 22, 1135-1140.
  • WitKamp, R. (2010). Biologically active compounds in food products and their effects on obesity and diabetes. In Comprehensive Natural Products II (pp. 509-545). Oxford: Elsevier.

Disclaimer: Our reviews and investigations are based on extensive research from the information publicly available to us and consumers at the time of first publishing the post. Information is based on our personal opinion and whilst we endeavour to ensure information is up-to-date, manufacturers do from time to time change their products and future research may disagree with our findings. If you feel any of the information is inaccurate, please contact us and we will review the information provided.

Have Your Say

3 comments on 'Glucomannan for Fat Loss – Is It Any Good?'

  1. Hi,my appetite has increased since I started on Glucomannan Cambogia instead of decreasing
    also I started going to the toilet once in 3-4 Days when before I was going once a day,Is it normal or should I stop taking it? Otherwise I feel well.

  2. Thank you Lady Yahingo for sharing your wife’s experience.
    This morning the same happened to me, I went to use the bathroom and saw the glucomannan pill intact. I got so upset because it looked like a big maggot and I got so scared. On close inspection, it was the pill still intact with its granules.

    That led me to googling about it, until I found this article. Atleast now I now that it doesnt mean there is something wrong with me or my digestion, it has happened to other people.

    I’m left wondering if it works at all then, cause in my case it was from the previous night.

  3. my wife was taking the glucomannan capsules 575mg 3 x aday. well she was upset when she had used the restroom after her meal and seen the glucomannan capsule in the toilet after having a bowel in reality the glucomannan capsule never did dissolve after she had taken and waited 30 minutes before she ate. along with not feeling full after meals.

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