Losing Weight With Glucomannan – Can It Treat Obesity?
Glucomannan is high in fiber, and fiber is being hailed as a nutrient that can contribute to weight loss. We look at the evidence to see whether glucomannan is worth including in your diet plan.
LAST UPDATED: March 2019 by Ben.
Author: Nicola Joyce.
All studies are cited with full references.
Fat Loss and Glucomannan
Can natural konjac root supplement help you lose weight?
Glucomannan – a natural extract from the root of the konjac plant – is cropping up in a huge range of weight loss support products, from replacement pasta and noodles to glucommanan powders and capsule supplements.
However, how does glucomannan work, and can it really help you lose weight faster?
- How does it work
- Weight loss
What Is Glucomannan?
Glucomannan is a natural water-soluble polysaccharide made of glucose and mannose extracted from the root of the konjac plant.
It is highly fibrous and absorbent and is used as a dietary supplement and food replacement to help people feel fuller and eat fewer calories.
That aside, it has a lot of health benefits, too.
Glucomannan can slow the amount of carbohydrate and sugars your digestive system absorbs, helping to maintain more stable blood sugar.
As a result, it can be an effective appetite suppressant, this is because it absorbs water and swells up in the stomach to help you feel fuller and less prone to snacking.
You will find glucomannan in powders and capsules, as an ingredient in weight loss supplements, shaped as rice/pasta/noodles for adding to meals, or as a konjac flour to thicken food.
Look for the words glucomannan, konjac root, zero noodles, or shiratake noodles – they are all the same thing.
Health Benefits Of Glucomannan
Glucomannan has strong evidence as a good weight loss support.
Yet, there is more to it than just weight loss.
Glucomannan has a ton of health benefits and can be a really useful addition to a healthy diet.
It can help maintain a healthy digestive system, treat constipation, and help reduce high cholesterol levels. If you don’t get a lot of fibre in your diet, it is well worth adding in.
How Does Glucomannan Work?
As a water-soluble fibre, you can imagine how glucomannan or konjac root helps you to stick to your diet.
First of all, it’s very low calorie in itself, so you can add zero noodles or rice to your meals for a lot of volume but barely any calories.
In addition it reduces the absorption of fat which will help you manage your weight.
Finally, glucomannan food products take up space in your stomach and help you feel fuller, so you actually eat less food but feel satisfied from your meals.
This study suggests that glucomannan slows carbohydrate absorption, probably by inhibiting the breakdown of complex carbohydrates into simple ones (making them harder to absorb). 
This 2004 study looked at applications of glucomannan, including in weight loss.
It concluded that glucomannan has plenty of pros but also some cons to consider:
“…this product is highly effective in the treatment of obesity due to the satiety sensation that it produces; as a remedy for constipation, because it increases the faeces volume; as hypocholesterolemic agent, interfering in the transport of cholesterol and of bile acids and as hypoglycemic and hypoinsulinemic agent, probably, by delaying gastric emptying and slowing glucose delivery to the intestinal mucosa….several disadvantages can be added as the production of flatulence, abdominal pain, esophageal obstruction, lower gastrointestinal obstruction or even the possible modification of the bioavailability of other drugs.” 
This 2005 critical review into glucomannan and obesity summarised various studies looking at its effectiveness and mechanisms for weight loss, and says that glucomannan can be effective as a weight loss support along with;
“…has been shown to improve lipid and lipoprotein parameters and glycemic status.” 
Then there is this older clinical study, a double-blind study carried out over 8 weeks to test the effects of glucomannan fiber in obese subjects.
The subjects did not change their diet or exercise habits, but still showed a mean loss of 5.5lbs over the 8 weeks (and also reduced their serum cholesterol and low-density lipoprotein cholesterol) – all with no side-effects. 
With this evidence in mind you may find that this cheap, natural, and safe dietary aid could be the help you need, your next step is to find a quality glucomannan supplement.
As we have already said, you can get glucomannan as a powder, in capsules, or as those zero type diet noodles and rice shapes.
To use the food items, simply replace regular rice, pasta, or noodles with the glucomannan alternatives.
They are tasteless by themselves, so be sure to add them to stir fries or pasta sauces (make sure the main dish is calorie controlled of course).
There’s no need to cook them – just heat them through for a couple of minutes with the dish you are eating.
They also have a long shelf life, so if you see zero noodles or other konjac root food replacements on offer, stock up!
You could try adding glucomannan plus ginseng to your daily intake, as they seem to work synergistically.
Glucomannan can modulate the rate of absorption of nutrients, and ginseng does a similar thing post-absorption.
To get the best effects from glucomannan as a weight loss aid, aim for 1g-5g glucomannan every day.
This can be from a konjac root supplement, powder, capsules, or glucomannan food item.
The addition of this cheap and simple plant fibre will help you feel full, avoid cravings, and eat fewer calories – all of which should really help you with achieving your weight loss goals.
This is why glucomannan is becoming a staple in more and more fat burner supplements, particularly those marketed towards women.
In many cases, difference is that men tend to want to cut fat, but that the same time still eat enough nutritious food to build lean muscle mass.
Whereas women prefer not to eat as much, this is where glucomannan helps due to making you feel fuller, for longer.
Therefore, take close attention to when you look for a fat burner supplement to see if glucomannan is included.
If so, ensure it is alongside other proven ingredients whereby you have full visibility of the amounts included for best results.
So, what do these findings say about glucomannan?
And, can it help you lose weight and burn fat?
Well, yes, the evidence points us that way.
By way of making you feel fuller you are less likely to eat more food, and less food means less calories.
Glucomannan also prevents and slows the digestion of carbohydrates and fat.
Therefore, this high fiber nutrient could be an effective way for you to shed those unwanted pounds.
 Dietary fiber and weight regulation. Howarth NC, Saltzman E, Roberts SB. Nutr Rev. 2001 May;59(5):129-39. Review. PMID: 11396693
 Dietary fiber decreases the metabolizable energy content and nutrient digestibility of mixed diets fed to humans. Baer DJ, Rumpler WV, Miles CW, Fahey GC Jr. J Nutr. 1997 Apr;127(4):579-86. PMID: 9109608
 Glucomannan: properties and therapeutic applications. González Canga A, Fernández Martínez N, Sahagún AM, García Vieitez JJ, Díez Liébana MJ, Calle Pardo AP, Castro Robles LJ, Sierra Vega M. Nutr Hosp. 2004 Jan-Feb;19(1):45-50. Review. Spanish. PMID: 14983741
 Glucomannan and obesity: a critical review. Keithley J, Swanson B. Altern Ther Health Med. 2005 Nov-Dec;11(6):30-4. Review. PMID: 16320857
 Effect of glucomannan on obese patients: a clinical study. Walsh DE, Yaghoubian V, Behforooz A. Int J Obes. 1984;8(4):289-93. PMID: 6096282
Nicola Joyce (aka “the fit writer”) is a fitness industry copywriter who has been writing for and about sport and fitness since 2004. Nicola is a competitive drug-free bodybuilder (with two World titles at amateur level) and has also competed in powerlifting and a couple of strongman comps. Prior to her strength training days, Nicola was an endurance athlete and has even swum the English Channel twice. She can be found on all social media at: thefitwriter.
Ben established this site to be a free resource in 2015. Since then it has gained over half a million visits. It explores the many avenues of fitness and uses supporting scientific evidence for any reviews or analysis of products.
Ben himself has been interested in fitness from an early age. He started playing rugby at the age of 6 for his town, county and school where he gained his full colors while also being in the Army Cadets. After graduating from university in 2005 with a BA(Hons) Ben moved to London and nurtured his love for weightlifting to support his rugby, he also became heavily involved with cycling. Ben also started skiing and recently joined the Army Reserve to further develop his capabilities.