Glucomannan Weight Loss: Does It Work?
Key Takeaways:
Glucomannan is a water-soluble fibre made from the roots of the konjac plant.
Glucomannan might help you feel fuller and change your gut bacteria to promote weight loss.
Research is mixed, though. In some studies, it’s not that effective for weight loss.
Ask your GP before adding glucomannan to your routine.
Glucomannan is a supplement that could aid weight loss. There’s some promising research, but it’s unclear how effective it really is.
Read on for our complete guide to glucomannan weight loss. We’ll cover what glucomannan is, whether it can help you lose weight, and the side effects to be aware of.
What Is Glucomannan?
Glucomannan is a water-soluble fibre that comes from the roots of the konjac plant — also known as elephant yams or devil’s tongue. You’ll find it in supplement form called glucomannan or konjac glucomannan (KGM).
It most often comes in a capsule, but you can also find glucomannan in food products, like noodles. And you can also find glucomannan and chromium, vitamins, and other types of fibre combined into one supplement.
Glucomannan is often marketed as a weight loss supplement because there’s some evidence it can help you lose weight.
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Does Glucomannan Work for Weight Loss?
Glucomannan might work for weight loss. Research is mixed, though.
A 2025 review of studies found that glucomannan supplementation in people with overweight or obesity was associated with reductions in:
Weight
Waist circumference
Body mass index (BMI)
On average, people lost about 3 kilos (kg), or roughly half a stone.
These results came from taking at least 5 grams (g) of glucomannan a day for at least 12 weeks. It’s not clear what other lifestyle changes participants made to promote weight loss.
In a small 2013 study, participants took either a glucomannan supplement or a placebo three times a day before meals. After 8 weeks, there wasn’t a significant difference in:
Weight loss
Body composition
Hunger or fullness levels
Participants in this study only took about 1 gram of glucomannan, though.
Ultimately, more research is needed on glucomannan to find out how it works, the best dose for weight loss, and the long-term effects.
Whether glucomannan works for you might depend on your gut bacteria, how much you take, how long you take it for, and your current body weight.
How Does Glucomannan Work for Weight Loss?
Glucomannan might work for weight loss because it’s high in fibre and has a thick, flow-resistant consistency (viscous). It can absorb and hold onto water, forming a gel-like substance in your stomach.
These properties may help it slow gastric emptying, or the speed at which food leaves your stomach.
With slower gastric emptying, you might feel fuller for longer, which can help you eat fewer calories and avoid snacking and overeating.
Glucomannan may also stimulate fullness (satiety) hormones, reducing your appetite. And it might change your gut bacteria in a way that promotes weight loss.
Other Health Benefits of Glucomannan
Glucomannan might provide other health benefits beyond weight loss.
Glucomannan might improve:
Blood sugar levels
Insulin sensitivity
Inflammation
Cholesterol levels
Bowel movements and constipation
Blood pressure
Gut health
Again, more research is needed on glucomannan and its potential health benefits.
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How to Take Glucomannan for Weight Loss
To take glucomannan for weight loss, start by checking with your general practitioner (GP) or another healthcare professional to ensure the supplement is safe for you.
Then, follow any instructions on the product you buy. You’ll usually take glucomannan with water.
Some research recommends taking 1 gram of glucomannan an hour before meals, three times a day, for weight loss.
But recommended dosages vary, and more research is needed to find the dose that gives the most beneficial effects.
Make sure you get glucomannan supplements from a reputable company. Check glucomannan reviews, look for third-party testing, and research the brand.
Tips to Maximise Weight Loss With Glucomannan
Glucomannan — or any other food supplement you’re considering — isn’t a magic pill. If it does aid weight loss for you, it’ll work best when combined with healthy lifestyle changes — especially eating fewer calories than your body needs.
Here’s what to include in your overall weight loss plan:
Eat a balanced diet. Go for fruit, veg, legumes, lean protein sources, complex carbohydrates, and healthy fats. In particular, foods high in protein and fibre can help regulate hunger.
Do more movement. This includes cardio, strength training, and general activity, like walking and standing.
Get enough sleep. Aim for 7 to 9 hours a night. Minimise sleep disruptors, like late meals, alcohol, screens, and caffeine.
Lower your stress levels. If possible, keep stress low. Try meditation, breathing exercises, and regular exercise to manage stress levels.
These healthy habits can help with both weight reduction and long-term weight management, whether you’re taking glucomannan or not.
Glucomannan Side Effects
Glucomannan is natural, but it can still cause side effects.
The side effects of glucomannan might include:
Burping
Bloating
Diarrhoea
Stomach pain
Farting (flatulence)
Uncomfortable feelings of fullness
Some of these side effects might only last for 1 or 2 hours after you take a glucomannan capsule. And they may only crop up during your first 1 to 3 days on the supplement. But everyone’s different.
If you take glucomannan, make sure you drink plenty of water to prevent gastrointestinal blockages and minimise side effects.
Who Shouldn’t Take Glucomannan?
Glucomannan isn’t right for everyone. You shouldn’t take glucomannan if you have:
A history of bowel obstruction
Problems swallowing (dysphagia)
Narrowing of the oesophagus
You also shouldn’t take glucomannan if you’re pregnant, breastfeeding, or taking diabetes medicines.
Plus, since glucomannan can slow gastric emptying, it might affect the absorption of any oral medication you’re taking.
Get medical advice to make sure it’s safe for you to take.
Alternatives to Glucomannan for Weight Loss
Alternatives to glucomannan include prescription weight loss medicines. These treatments have more research behind them showing they’re effective at helping people with overweight and obesity lose weight.
Many weight loss medicines work by reducing your appetite and making you feel fuller.
For example, you may be eligible for weight loss injections like:
You can also get oral weight loss medications, like naltrexone-bupropion (Mysimba®) and orlistat (Xenical®, Alli®, Orlos®).
Speak to your GP or connect with a private clinician to find out if weight loss medicines are right for you.
You can connect with a private healthcare professional online through the Hers U.K. platform.
Glucomannan Weight Loss: In Summary
Glucomannan is a promising weight loss supplement, but more research is needed to know if it really works — and by how much.
Here are the key facts:
Glucomannan may support weight loss. It can help you feel fuller, making it easier to stick to nutritious foods, practice portion control, and eat the right amount of calories for you.
Research is promising, but mixed. Some studies link glucomannan supplementation to a lower body weight. Others show it doesn’t affect weight. It might depend on your biology, lifestyle, and the dose you take.
Glucomannan isn’t right for everyone. Check with your GP or a private clinician to make sure the dietary supplement is right for you. Side effects include bloating, gas, and diarrhoea.
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FAQs
Get answers to frequently asked questions about glucomannan weight loss below.
Does glucomannan help weight loss?
Glucomannan might help with weight loss. Some research shows glucomannan supplements are linked to weight loss. However, other studies show glucomannan has no effect on weight. More clinical studies are needed.
How long does glucomannan take for weight loss?
It’s unclear how long glucomannan takes to promote weight loss. Some research suggests you might see weight loss in 12 weeks. But it might depend on your lifestyle, the dose you take, and your biology.
How much weight can you lose with glucomannan?
Some research suggests you might lose an average of about 3 kilos (roughly half a stone) on glucomannan, but individual results vary. How much weight you lose can depend on your lifestyle, biology, and the dose of glucomannan you take.
This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your GP about the risks and benefits of any treatment.