If you’ve been exploring natural ways to support weight loss, you may have come across glucomannan—a plant-based fibre that’s been making waves in the supplement world. Derived from the root of the konjac plant, glucomannan has gained attention for its ability to help you feel fuller for longer, potentially making it easier to reduce calorie intake without relying on prescribed medication. But does it actually work, and is it safe to take?
If you’re considering whether to include glucomannan in your weight loss plan, we’re sure you’ve got some questions. Read on—you’ll find the answers below.
What is glucomannan?
Glucomannan is a popular weight-loss supplement. It’s a water-soluble dietary fibre that’s extracted from the roots of the konjac plant, also known as elephant yam. Glucomannan can comprise up to 60% of a konjac, and sometimes people use the terms interchangeably. Have you ever eaten shirataki noodles? They’re long, white noodles that are high in fibre and very low in calories—which makes them an ideal choice when eating to support weight loss. And they’re made from glucomannan.
Notably, glucomannan is great at absorbing water (it can absorb up to 50 times its weight in water!) and when this happens, it becomes a thick gel.
What does glucomannan do in the body?
By forming a bulky gel in your stomach, glucomannan helps you stay fuller for longer.
Glucomannan and weight loss
You can get glucomannan, aka konjac, weight loss supplements as capsules or powder. Sometimes, it’s used as a food additive—often as a thickener and emulsifier.
So, how exactly does glucomannan help with weight loss? The natural appetite suppressant is believed to promote weight loss in a few different ways:
- It contains almost no calories, making it a filling addition to your diet without adding to your daily energy intake.
- Because it’s a fibre, the body can’t break it down, which means that it can slow down the rate of digestion. This can help keep your appetite at bay after eating.
- Because this gel is really firm, it sits in the stomach for longer—and once there, it can absorb water and expand. Here, glucomannan acts as an appetite suppressant, because both of these factors can keep you feeling fuller for longer.
- Some research suggests its effects might decrease the amount of cholesterol your gut absorbs from your food, too.
So does glucomannan work for weight loss?
But is glucomannan good for weight loss? Potentially. The scientific evidence on glucomannan shows some weight loss success stories—though these results are modest.
In one trial of 176 people, taking glucomannan supplements alongside a reduced-calorie diet (1,200 calories per day) led to more weight loss than for those just following the diet and taking a placebo. And in terms of the glucomannan before and after results: Over five weeks, those using the supplements lost 3.8kg on average, versus 2.5kg for the placebo group.
This is in line with other studies that found that glucomannan might have a small benefit for weight loss. Though there’s also research showing that it has no notable effect on weight—like this review of nine clinical trials or this 8-week trial of 53 people.
Glucomannan is broadly considered safe to take, so if you’re using it and feel it’s working for you—that’s great. And if not, there are plenty of other treatment options out there.
Glucomannan benefits
But that’s not all glucomannan might be able to help with. Many people choose to buy glucomannan capsules to take advantage of these added benefits:
Improved cholesterol
There’s some evidence showing that glucomannan could help to lower “bad” cholesterol (but again, there are also studies showing no significant effect here).
Lowering cholesterol is thought to happen in a few ways. Firstly, by slowing down digestion, glucomannan can prevent the liver from producing cholesterol. And as we mentioned earlier, it might also reduce the amount of cholesterol your gut absorbs from your food—and increase the amount that’s passed out in your stools.
Blood sugar
When glucomannan forms a gel inside your stomach and slows down digestion, this slows the rate at which sugar is absorbed by your gut. This can help keep your blood sugar levels in check.
And from a weight loss perspective, this is good news because excess blood sugar can be stored as fat.
Gut health
A fibre-rich diet helps your gut stay balanced and healthy. Glucomannan has been shown to regulate gut bacteria. That is, it fuels the “good”, health-promoting bacteria and keeps levels of others under control to prevent them from causing problems. This can have a bunch of positive knock-on effects, like easing constipation.
Glucomannan side effects
While common side effects are usually mild, some people may experience gut-related issues like bloating, flatulence, diarrhoea, and stomach pain. These symptoms typically subside as the body adjusts, but they can be more pronounced if too much is taken or if it's not consumed correctly.
So now you’re probably wondering, is glucomannan safe? It’s generally considered safe to take, especially when used short-term and as directed. Most studies focus on its effects over a limited period, so the long-term safety profile isn't fully understood. That means it's best to use glucomannan with caution and avoid prolonged use unless advised by a healthcare professional.
It’s crucial to take glucomannan with plenty of water—at least one to two full glasses. This allows it to reach the stomach before expanding into a gel. Without enough water, there’s a risk it may swell too early, potentially leading to choking or blockages in the throat or digestive tract. In fact, due to this risk, glucomannan in tablet or dry powder form has been banned or restricted in some countries, including Australia and parts of the EU.
Taking too much glucomannan can increase the risk of digestive blockages and may interfere with the absorption of medications or nutrients.
Heads up: There isn’t enough evidence to recommend glucomannan for children, pregnant or breastfeeding women. And do check in with your doctor before taking glucomannan if you’re using any medications that affect blood sugar.
How to take glucomannan for weight loss
The general advice on the recommended glucomannan dosage for weight loss is to take 1g three times per day, around one hour before a meal.
And if you really want to get the most out of your weight loss plan, it’s best to take glucomannan alongside a healthy diet and regular exercise. In fact, studies note that the beneficial effects of glucomannan may be enhanced via diet—namely, eating fewer calories than you burn each day.
FYI: There isn’t necessarily any “best” glucomannan pills for weight loss. What matters is how much glucomannan is in them (so you can ensure you’re getting the right dose) and whether it’s been mixed with other ingredients for a compounded effect.
For instance, glucomannan and chromium—which can help keep blood sugar under control—are often combined. Voy’s Glucomannan Complex capsules bring these ingredients together with green tea, offering a convenient supplement option.
Can you take glucomannan powder for weight loss?
Yes—as long as you stick to the recommended dosage and wash it down with a glass of water.
Taking glucomannan for weight loss with other medicines
Certain dietary supplements can interact with other medicines. So it’s best to check with your clinician whether glucomannan is safe and suitable for you. They’ll be able to review your medical history and any other medication you’re currently taking.
As glucomannan can lower blood sugar, it should be used with caution by people taking other medicines that impact blood sugar. Glucomannan may also reduce the absorption of other medicines, so it’s usually recommended you take your other medicines one hour before, or four hours after taking glucomannan.
Other weight loss treatments to know about
With weight loss supplements, we know that a big part of their appeal is how convenient they are to take. But there are plenty of other options worth knowing about, too—like weight loss medicines which have been studied in more detail.
There are also injections, like Wegovy and Mounjaro, that can lead to losses of up to 25% of your starting weight. Or there’s orlistat, a pill that can support over 10% weight loss in some people.
Your weight loss journey is as unique as you are—and with the help of our expert coaches and clinicians, you can create a treatment plan that’s perfectly tailored to your needs and goals. It’s part of our weight loss programme. As well as one-to-one support, you’ll get weekly medication and an app to track your progress. We know the journey might seem long, but we’re in it with you every step of the way. And we know you can do it.
You can take your next step right now. Find out if you’re eligible by filling out this form—it’ll take less than five minutes.
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