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, a type of fibre that comes from a root vegetable called konjac. So, it probably won’t surprise you to learn that glucomannan is a popular weight-loss supplement.
If you’re considering whether to include glucomannan in your weight loss plan, we’re sure you’ve got some questions, like: how exactly does it work, and how much weight might I expect to lose? Read on—you’ll find the answers below.
What is glucomannan?
It’s a natural 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.
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.
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. When you take glucomannan supplements, the gel forms in your stomach.
Glucomannan supplements and weight loss
So, how exactly does glucomannan help with weight loss?
For one, it contains almost no calories. And 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.
Just now, we mentioned that glucomannan forms a gel once you take it. 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. Its effects might decrease the amount of cholesterol your gut absorbs from your food, too.
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 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 which 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.
Benefits of glucomannan supplements
But that’s not all glucomannan might be able to help with.
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 lowers the amount of sugar that’s 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.
Can glucomannan cause side effects?
It might, though it’s generally considered safe to take. But because studies mostly look at its effects over the short term, we don’t know much about the potential risks of taking it for long periods of time.
Common side effects include gut-related issues like flatulence, diarrhoea, and stomach pain. Usually, these are mild.
And be sure to wash down glucomannan supplements with plenty of water! This ensures they’ll form a gel only when they reach your stomach—otherwise, there’s a risk of swelling, which can cause blockages in your throat and gut. Capsules are a good shout here because their outer shell keeps the glucomannan from touching water until it gets to your stomach.
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 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.
Can you take glucomannan powder for weight loss?
Yep—as long as you stick to the recommended dosage and wash it down with a glass of water.
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 around 15-25% of your starting weight. Or 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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