It’s a pattern that will be familiar to almost anyone who has tried to lose weight.
It starts well – meals planned, good intentions intact. Then hunger kicks in.
You hold the line for a while. But eventually resolve slips. A biscuit. A chocolate bar. A bag of crisps.
The diet wobbles – then collapses altogether.
If only there were something that could blunt those hunger pangs, rein in cravings and break the cycle of restriction, guilt and bingeing, you may think.
That, some experts now claim, is exactly what a little-known supplement called glucomannan can do.
And unlike many weight-loss aids on the market, there is at least some scientific evidence behind it.
This week, Kate Donohoe, a 44–year–old personal trainer, revealed that glucomannan helped control her appetite – and weight – after losing 140lbs.
Kate Donohoe, from the UK, ordered a tub of glucomannan from Amazon for her weight loss journey. She says it has helped to ease urges and cravings she has had around food
Despite watching what she ate, Donohoe said she struggled to silence the ‘food noise’ – constant, intrusive thoughts about eating, cravings and the urge to snack, even when not physically hungry that many with weight struggles suffer.
She was considering taking weight loss drug Mounjaro, when a friend suggested she try glucomannan, which, they insisted, was a natural alternative.
‘I had no expectations, but I figured it couldn’t hurt,’ Donohoe said.
The effect, she claimed, was remarkable.
‘Within two days, I had no cravings. There was nothing I hankered for. I could eat a balanced diet and I wasn’t obsessed or thinking about food.’
So what is glucomannan, and could it really be the Holy Grail slimmers have been looking for – a simple, cheap, and side effect-free way to make losing weight, and keeping it off, far easier?
We spoke to the experts to find out what you need to know.
What is glucomannan – and how does it work?
Glucomannan is a type of soluble fibre extracted from the root of the konjac plant – the same ingredient used to make so-called zero-calorie noodles.
It has been used for over 2,000 years in traditional Chinese and Japanese medicine and food.
But around 2023, amid the explosive rise of new weight loss drugs, the supplement began gaining traction online as a so-called ‘budget Ozempic’, or a cheap way to curb appetite.
Once consumed, it absorbs water and expands in the stomach, forming a thick, gel-like substance. This slows the rate at which food leaves the gut and can help people feel fuller for longer, potentially reducing overall calorie intake.
‘Glucomannan is not the perfect fix for every patient, but it can help someone to lose a few pounds,’ cardiologist Dr Sirisha Vadali told the Daily Mail.
‘It may be a good option for those who don’t want to reach for the Ozempic.’
Will glucomannan actually help me to lose weight?
More than 15 studies involving hundreds of people have investigated glucomannan as a weight loss supplement – and the results are encouraging.
Earlier in her life, Kate, a 44–year–old personal trainer, said she lost more than 100lbs by radically overhauling her diet and lifestyle. She is shown above with a glucomannan capsule
A 2025 review of 10 papers found overweight or obese people who took glucomannan for between five and eight weeks lost 7.4lbs on average – equivalent to nearly 1lb a week.
Meanwhile, a separate 2024 study involving 112 overweight adults found those who took glucomannan and two other supplements lost 13.3lbs over six months – or about 0.6lbs per week.
For comparison, those given a placebo in the same study lost just 4.8lbs, equivalent to around 0.2lbs every seven days.
In most studies, participants weren’t taking the supplement in isolation – they were also on a diet, eating fewer calories than they burned.
In one trial, that meant cutting around 500 calories a day.
But some evidence suggests the supplement may still lead to weight loss even without deliberate calorie restriction.
In an older paper from the 1980s, obese women who took the supplement without dieting lost about 5.5lbs in eight weeks – roughly 0.7lbs per day.
Vadali told the Daily Mail she’d had at least two patients who used the supplement to lose weight, and both said they lost a few pounds while using glucomannan.
She said that, in general, studies showed it led to moderate weight loss.
How and when should I take glucomannan?
In studies on glucomannan for weight loss, participants follow a strict regimen.
Generally, they consume glucomannan as a capsule, although some studies gave the supplement to participants as a powder.
Participants take it about three times per day, normally on an empty stomach and shortly before a meal. They wash it down with one to two glasses of water.
There was some variation on exactly when to take it before a meal, although it was generally recommended from 15 minutes to an hour beforehand.
Participants generally took one or two capsules for each dose, or one to four grams of the glucomannan powder.
Experts warned not to take too much, warning that this could swell in the stomach and cause other complications.
They said it was important to take the supplement with one to two glasses of water to ensure it was washed into the stomach before it expanded, slashing the risk of it swelling in the wrong place and causing choking.
How rapidly will I lose weight on glucomannan?
People can lose as much weight on the supplement as an Ozempic user – but only if they are also dieting.
Evidence for this includes a 2005 study by Norwegian scientists where 167 overweight adults took the supplements daily for five weeks.
They also ate 1,200 calories per day.
Overall, participants lost 8.8lbs – equivalent to about 1.8lbs per week.
That is roughly similar to the weight loss recorded among weight loss shot users, who typically expect to lose between 1 to 2 lbs per week while on the drug.
Does glucomannan cause any side effects?
Despite it being a natural supplement, experts warn that those taking glucomannan may also experience side effects.
Those taking the supplement have reported experiencing mild effects such as bloating, flatulence, diarrhea and stomach pain.
Doctors and health officials warn that taking the supplement without water may be unsafe, saying the product could cause choking or other serious effects.
Could glucomannan put me at risk of malnutrition?
Nutritionist Rob Hobson, author of Every Bite Counts warned that, without careful thought, relying on glucomannan alone to aid weight loss could have downsides.
‘The problem with these kinds of products is that people end up using them as a shortcut – filling up without actually eating properly,’ he said.
‘If you’re already dieting and restricting your intake, and then you layer something like this on top, you risk not getting enough nutrients.
‘When you’re eating less, what you do eat needs to count.
Nutritionist Rob Hobson, author of Every Bite Counts warned that, without careful thought, relying on glucomannan alone to aid weight loss could have downsides
‘Glucomannan doesn’t offer much in the way of vitamins or minerals – there’s nothing in them. They target appetite, which is only one small part of weight loss.’
‘At the end of the day, it is just a purified fiber,’ adds Vadali.
Can glucomannan lower cholesterol levels?
Studies suggest that glucomannan has several health benefits besides weight loss.
A 2024 meta-analysis of 11 studies suggested that the supplement may lower cholesterol levels, which are linked to a higher risk of a heart attack and stroke.
Researchers said this was likely because it formed a viscous gel in the intestines, which stopped bile acid from being reabsorbed.
It has also been linked to an improved microbiome.
In the 2025 paper previously mentioned, scientists found those on the supplement also had more ‘good’ bacteria in their gut – including Bacteroidetes, Akkermansia and Bifidobacterium. Fiber tends to fuel the growth of good bacteria.
Vadali told the Daily Mail that studies suggested the supplement helped to improve cardiovascular health.
Should some people avoid glucomannan?
Vadali, who is based at HonorHealth in Arizona, warned that if someone had swallowing difficulties or any abnormalities in their esophagus or intestines that they should talk to their provider before taking the supplement.
Health officials in the US, Australia and Canada have urged people to use the supplement responsibly.
In the US, the FDA issued a warning in 2001 after Konjac candy – fruit–flavored gels containing the supplement – were named a choking hazard and linked to six child deaths nationwide.
It has not banned glucomannan, however, and has approved it for use as a food additive and thickener. It is still available as a dietary supplement.
Health officials in Canada warned in 2010 that glucomannan supplements posed a significant choking hazard, saying they should always be consumed with water. The country has not banned the supplement.
In Australia, health officials have banned glucomannan in tablet form amid concerns over a high risk of choking or suffocation.
Although studies suggest it has real potential as a weight loss-inducing supplement, doctors say it is no substitute for a balanced and healthy diet.
‘A high–protein, high–fibre diet is the best way forward for those looking to lose weight,’ said John Lukey, a dietitian in the UK.
For Donohue, she said she would recommend glucomannan to anyone looking to lose weight.
‘Alongside diet and exercise, glucomannan could make weight loss easier for anyone trying to give it a go,’ she said.
‘That’s why it would be my first port of call before trying weight loss jabs.’
