Can’t afford fat jabs? Our experts have the natural alternatives

Social media is awash with ‘natural’ GLP-1s – cheaper, seemingly more holistic options that mimic effects of the natural GLP-1 appetite hormone – with plant-based ingredients claimed to be viable alternatives to curb your appetite and shed unwanted pounds.

With early evidence to suggest some such as berberine (derived from a shrub where it is found in roots and stems) could lead to up to a 4kg loss in three months, they have added appeal if you’re someone who just wants to lose a bit of weight before the summer – or whose weight loss using other approaches has plateaued – and don’t want to go on drugs that have nasty potential side-effects, such as nausea, diarrhoea and hair loss. (Or frankly, if you can’t face the idea of having to inject yourself.)

But while Wegovy and Mounjaro are backed by scientific evidence, just how safe and effective can a natural supplement be?

Weight-loss jabs contain drugs such as semaglutide, which work by mimicking glucagon-like peptide-1 (GLP-1), a natural gut hormone that tells the brain you are full, slows stomach emptying and helps the pancreas release insulin to manage blood sugar.

Our body’s own GLP-1 only lasts for a few minutes after being released, but the synthetic drug versions last for a whole week.

And since the landmark research in 2022 demonstrated unequivocally that people could lose up to 11 per cent of their body weight taking GLP-1s, demand has skyrocketed.

But in the UK monthly jab costs of Mounjaro rose last year to around £120-£330 per month and although Wegovy remains cheaper at £75-£299, this still puts them out of the price range of many people.

Supplement companies have been quick to jump on the appetite-suppressant bandwagon with more affordable plant-based products – costing just £3 to £50 per month in comparison.

Duane Mellor, a dietitian and an honorary associate professor at the Diabetes Research Centre at the University of Leicester, says: ‘Many contain nutrients and plant extracts which manufacturers claim can slow gut emptying and the breakdown of nutrients – just like GLP-1s.

‘The research there is for them shows for the most part that any benefits they might have are likely to be limited and inconsistent – and the side-effects can be similar to GLP-1s, including digestive issues.’

But while it’s clear they do not match up to GLP-1 medication in terms of dramatic weight loss, some of these plant extracts have shown potential for improving metabolic health by helping balance blood sugar, while others create a feeling of fullness that can reduce overeating – all of which may result in modest weight-loss in the range of 1-2kg over several months – or even 4kg in the case of berberine.

And that may be enough for some who don’t need to lose significant amounts of weight or whose weight loss has levelled out.

In this comprehensive guide, we asked Duane Mellor and Iain Brownlee, an associate professor of human nutrition at Northumbria University, for their expert view on some of the most popular natural weight-loss supplement ingredients now on the shelves…

Berberine

Average cost per month: £15-£40

Claim: While often nicknamed ‘nature’s Ozempic’, this plant alkaloid (a nitrogen containing natural compound) works in a very different way from GLP-1 medications. Its main benefit is thought to be triggering the release of AMP-activated protein kinase (AMPK), an enzyme that lowers high blood sugar levels and that tells the cells to burn stored fat for energy.

Average weight loss: 1-4kg (over 8-12 weeks)

Berberine releases an enzyme that lowers high blood sugar levels and that tells the cells to burn stored fat for energy

Expert verdict: ‘While laboratory and animal studies show some promise, human clinical evidence is still limited,’ says Duane Mellor. ‘Detailed reviews of all existing trials show modest results, including one published in the Journal of Clinical Nutrition in 2022 – with people losing around 1-4kg (2-9lb) over eight to 12 weeks when taking 900-1,500mg per day.

‘US experts including Harvard Medical School have noted that it’s not as effective as medications such as Ozempic – and should be compared more to metformin, so could help people control blood sugar spikes and food cravings. Although again it is nowhere near as effective as this prescription medication.

‘However, like metformin, berberine can cause gut issues such as stomach cramps and diarrhoea.

‘It’s also been shown to inhibit several liver enzymes responsible for breaking down some drugs (e.g. blood-thinners and statins), which could lead to dangerously high levels of those drugs in your system.

‘So if you’re taking medication or have other health conditions, discuss taking berberine with a health professional before you start.’

NMN

Average cost per month: £25-£45

Claim: NMN (nicotinamide mononucleotide) is a form of vitamin B3 our bodies use make a natural chemical known as NAD+, which is crucial for turning the food we eat into energy. It’s thought to aid weight loss by helping to fire up the metabolism to burn calories faster and improve insulin sensitivity to help balance blood sugar and control food cravings.

Average weight loss: 1-2kg (per month)

Expert verdict: ‘NMN supplements are relatively new to market and although they appear to have a metabolism-boosting effect when studied in a lab, this doesn’t always equate to significant weight loss when taken as a daily supplement,’ explains Iain Brownlee.

‘There have been a few small individual studies that have suggested some positive impacts, including one in 2023 by Harvard Medical School which found that when 30 middle-aged obese people took 2000mg of NMN daily, they had a significant reduction in cholesterol levels and body weight after a month, compared to those taking a placebo.

‘But a 2024 analysis of available findings from human studies of NMS supplements found no improvement in body weight, blood sugar and cholesterol levels when compared with a placebo, reported the journal Critical Reviews in Food Science & Nutrition.

‘Some short-term users get mild nausea or bloating – but it’s generally well tolerated over a few weeks.

‘Plus, excess levels (potentially of 1,000mg or more) of nicotinamide (which NMN contains) over a long period have recently been linked to an elevated risk of heart attack and stroke, possibly due to inflammation in the arteries, so caution is needed.’

Apple cider vinegar

Average cost per month: £1.55-£15

Claim: Made from fermented apples, this has been hailed by some as useful for weight loss due to its acetic acid content, which works to slow the rate at which we absorb food – similar, advocates say, to the action of a GLP-1. It is also claimed to help balance blood sugar.

Average weight loss: Unknown but probably small.

Expert verdict: ‘A few small human studies suggest apple cider vinegar could help with weight loss, but results have been inconsistent and it certainly won’t “break down fat” as many supplements claim,’ says Duane Mellor.

‘One 2021 review found it may lower blood sugar spikes after meals, which could have a moderate impact on weight, although this is largely related to delaying how quickly food leaves the stomach before being digested.

‘But any vinegar would have the same effect. A side-effect frequently reported was nausea.

‘Also, to get the therapeutic dose of 1.5g of acetic acid used in studies you need 30ml of apple cider vinegar daily, so supplementation is only practical in liquid form, not in the many pills or gummies on the market.

‘So it’s better to use it in salad dressings and other foods rather than taking it separately as a supplement.’

Glucomannan

Average cost per month:  £16-£40

Claim: A fibre that comes from the root of the Asian konjac plant, glucomannan absorbs nearly 100 times its volume in water when consumed, stretching the stomach. This triggers the release of hormones linked to fullness and acts as an appetite suppressant, say advocates. The viscous gel is also said to slow the absorption of carbohydrates and fats, which can help stabilise blood sugar and may therefore curb cravings.

Average weight loss: 1.3kg (over five weeks)

Expert verdict: ‘While some early studies reported significant weight loss (around 5.5lb over 8 weeks), more recent reviews comparing all existing studies – including one by the University of Exeter in 2014 – have found no statistically significant difference between glucomannan and placebo for overall weight reduction,’ says Duane Mellor.

‘When benefits are found, they are typically described as “modest” or “small”. For example, one often cited Norwegian trial in 2005 of 176 people showed those taking the supplement lost roughly 1.3kg (2.9lb) more than the placebo group over five weeks with a dose of around 2-4g per day.

‘As a high-fibre plant, it can cause mild side-effects such as bloating, gas or diarrhoea. And it should be avoided by people with swallowing difficulties or any structural gastrointestinal issues (such as Crohn’s or diverticulitis), as it can expand before reaching the stomach and could potentially cause a blockage.

‘That’s why it’s also important that anyone taking it drinks plenty of water to make sure it moves smoothly through the digestive system.’

Green tea

Average cost per month:  £6-£25

Claim: This tea contains caffeine and antioxidants called polyphenols – both have been found in lab settings to speed up the rate at which our cells burn fat, leading to the idea that taking it in high-dose supplement form could lead to weight loss.

Average weight loss: 1-1.8kg (over 12 weeks)

Expert verdict: ‘Understandably the idea of an ingredient being “fat-burning” sounds as if it would help directly with weight loss, but this often isn’t the case,’ says Iain Brownlee.

‘Even substances that seem to speed up the metabolism of fat in animal or human studies, in real terms often only results in very short-term effect that happens soon after swallowing them – which just isn’t enough to result in significant weight loss.

‘As a result, the vast majority of human studies on green tea extract have shown no real effect when it comes to weight loss. The few studies that have suggested benefits have used very high doses of green tea extracts – five to 15 times higher than you would get from drinking one cup of green tea.

One 2020 review of studies found slight weight loss effects (1kg-1.8kg over 12 weeks) but only when the dose of green tea extract was over 500mg and up to 1500mg a day (one cup contains 80-90mg – having eight or more cups is considered dangerous due to the high caffeine content).

‘High doses of green tea extracts in supplement form have been flagged by the European Food Safety Authority as having high potential to cause liver damage. So any small potential for reward is far outweighed by the serious risk to health.’

Inositol

Average cost per month: £13-£35

Claim: Inositol is a natural-occurring sugar, with myo-inositol the most common form found in supplements. It’s believed to aid weight loss mainly by improving insulin sensitivity and correcting hormonal imbalances. It appears to act as a chemical messenger helping cells respond more efficiently to insulin, which may in turn reduce fat storage and lower blood sugar levels. Supplements contain around 4000mg, equivalent to eating 16 slices of wholemeal bread (one of the best food sources).

Inositol is believed to aid weight loss mainly by improving insulin sensitivity and correcting hormonal imbalances

Average weight loss: 0.4-0.6kg (over two to three months)

Expert verdict: ‘Myo-inositol isn’t a standalone fat burner nor does it substantially reduce appetite,’ says Duane Mellor.

‘But recent research show that it does have some benefits for metabolic health – especially for those with polycystic ovary syndrome [a hormone-related condition in women] or insulin resistance [a precursor to type 2 diabetes, where the cells stop responding properly to insulin].

‘A 2025 analysis of 18 clinical trials published in Frontiers in Endocrinology found it could significantly reduce BMI, waist-to-hip ratio and waist circumference for people in these groups.

‘It does seems make cells respond more efficiently to insulin and lower blood sugar levels. However, researchers note that overall weight loss is often modest, typically around 0.4 to 0.6 kg over two to three months, so it’s not a magic bullet for those looking for larger amounts of weight loss.

‘Some people experience nausea, stomach cramps or diarrhoea on it.’

White kidney bean extract

Average cost per month: £5-£10

Claim: White kidney bean extract, concentrated from the beans, is said to aid weight loss by blocking amylase, the enzyme responsible for breaking down carbohydrates into absorbable sugars, so more are passed out simply as waste. This in turn reduces overall calorie absorption, lowers blood sugar spikes and may enhance fullness, which together could result in some weight loss say proponents.

Average weight loss: 1.6kg (over eight to 12 weeks)

Expert verdict: ‘Reducing the activity of just one of the many digestive enzymes in the gut is not necessarily going to result in substantial weight loss,’ cautions Iain Brownlee.

‘But a review published in the journal Nutrition Research this year looking at eight studies (taking 1,500mg to 3,000mg per day) was favourable and found a modest but fairly consistent impact on body weight reduction – with people losing 1.6kg on average over eight to 12 weeks.

‘It’s generally considered safe for short-term use, with minor, often temporary, digestive side-effects at first, including gas, bloating, stomach cramps and diarrhoea.

Taurine

Average cost per month:  £5-£10

Claim: Taurine is a natural compound found in shellfish, dairy and meat. Studies have found that people who are low in taurine are more likely to be low in naturally occurring GLP-1.

Average weight loss: 0kg-1kg over eight weeks

Expert verdict: ‘In animal studies, it has been shown that taurine molecules can boost GLP-1 levels and improve glucose metabolism,’ explains Duane Mellor, ‘but so far, in humans, research suggests taurine only has a limited benefit in diabetes and weight management.

‘While it does appear to increase natural levels of GLP-1 in the body (at doses of around 3g per day) the overall effect on appetite and weight is none to modest in most research – losing 0kg-1kg over eight weeks.

‘This is because levels of the natural version of this hormone fall by a half less than five minutes after eating – unlike drugs such as Wegovy and Ozempic where it stay at high levels or a whole week.

‘Another downside it that the higher doses found in taurine supplements – 2g or more – can cause nausea, vomiting, and diarrhoea.’

Psyllium husk powder

Average cost per month: £2-£12

Claim: Psyllium husk powder – the ground-down seeds of the plantago ovata plant, grown in the Mediterranean – is said to help weight loss by acting as a soluble fibre that expands in the stomach, increasing fullness so suppressing appetite. By slowing down the absorption of carbohydrates, it’s also thought to help prevent spikes in blood sugar and control food cravings.

Average weight loss: 2.1kg (over five months)

Psyllium husk powder is said to help weight loss by acting as a soluble fibre that expands in the stomach

Expert verdict: ‘Psyllium forms a gel in the presence of water that is retained is the gut,’ says Iain Brownlee. ‘But reducing appetite will only lead to weight loss if they continue beyond a single dose of a supplement like psyllium husk.

‘A 2023 review of six studies, published in the Journal of the American Association of Nurse Practitioners, found a modest but consistent impact of around 2.1kg weight loss in five months taking around 5g of psyllium husk immediately before meals.

‘This pre-loading approach would need to be paired with careful choices of nutritious and balanced meals to make sure you get adequate overall calories, protein, vitamins and minerals – or you could find yourself low in some nutrients.

‘You also need to drink plenty of water with it. It can cause temporary digestive issues like bloating, cramping and gas at first.’