Online marketplaces flooded with misleading weight-loss supplements, Which? warns
Which? has found bogus weight-loss claims about supplements on both online marketplaces and popular health retailers, as the consumer champion calls on the government and regulators to crack down on businesses flouting advertising rules.
In November and December 2025, Which? researchers looked at weight-loss supplements listed for sale on popular online marketplaces and health retailers - including Amazon, eBay, Holland & Barrett, Superdrug and Temu among others - to see if the claims they were making stood up to scrutiny.
In the UK, companies cannot make health claims about a product without any evidence. If a business wants to advertise their product with a specific claim it must either be on the approved or the ‘on hold’ register.
The health claims register, held by the Department of Health and Social Care (DHSC), shows what businesses can - and can’t - say an ingredient can do for people’s health, and the wording and conditions for its use are often very specific.
However, Which? found evidence that many brands seem to be making outlandish claims, with little enforcement of the rules to stop them.
For example, the consumer champion saw Extreme Burn supplements by a business called Formula Max 5 listed on eBay. The product claimed that including raspberry fruit extract ‘assists the body to burn fat at a higher rate’ and the addition of green coffee bean ‘decreases the absorption of carbohydrates’.
In reality, a slew of weight loss claims for raspberry extract were all rejected by the health claims register owing to a lack of compelling evidence, while the green coffee bean claim that it ‘acts by reducing the absorption of sugar (glucose) from the digestive tract’ was also rejected.
Which? also found that several well-known health retailers like Holland & Barrett and Superdrug had product categories on their website for ‘fat burners’ and ‘appetite suppressants,’ despite the fact some of the tablets listed in these categories do not make any weight loss claims.
For example, at Holland & Barrett, Acai Berry tablets were listed under the ‘fat burner’ section of the website. However, the page and packaging for their Acai Berry tablets made no claims of any kind – because the tablets do not contain any ingredients with authorised or on-hold weight-loss claims.
Similarly, Superdrug’s ‘appetite suppressant’ section included a cinnamon supplement which makes no claims of its own to impact appetite. Listing these products on ‘fat burner’ and ‘appetite suppressant’ pages could be misleading for shoppers who might purchase these items thinking they help with weight loss.
Even more worryingly, Which? also saw products listed for sale on online marketplaces which make unfounded claims to target certain areas of the body or be as effective as weight-loss jabs.
The Advertising Standards Authority (ASA) rules state that products cannot say how much weight customers lose or how quickly, or from which part of the body - as this is something brands simply cannot predict.
However, Which? found a 'keto fat burner' supplement from the brand Pslalae on Temu claimed that customers would ‘lose your belly fat fast while you shred your stomach’, while the 'slimming capsule' from the brand Coolkin, also on Temu, claimed that customers can ‘reduce waistline’ and ‘slim & tone stomach’.
Similarly, a product called ‘Gone Appetit’ from Internal Youth on Amazon suggests that within four weeks ‘you're losing centimetres from your waistline’ and within eight weeks ‘you're mentally free from food obsession’.
Products are also not able to claim that they can have the same effects as prescription medicines - like weight-loss jabs. If products make medicinal claims, they can be considered medicines and will be regulated by Medicines Healthcare products Regulatory Agency (MHRA).
On eBay, Which? found a listing for Phentramine 375 by Pharmaslim, asking: “Why use prescription weight loss pills when you can get non-prescription weight loss pills that have no negative side effects but are just as effective?” Not only is this not permitted under medical laws by claiming to be ‘just as effective’ as a prescription medication, but risks further confusion by being named similarly to a recognised weight loss drug, Phentermine.
The consumer champion reported all its findings to the retailers - leading to more than 50 misleading weight-loss supplement listings being taken down.
Over the last six months, Which? has repeatedly found examples of misleading and unsafe supplements being listed on some online marketplaces and popular health retailers.
Regulation of the supplement industry cuts across several regulators and government bodies but they are failing to keep pace with how quickly the industry has boomed and the types of products now sold.
Better oversight is desperately needed to make sure misleading products are taken off the market. The government must ensure there is strong enforcement in place so that any companies breaking the rules - whether manufacturers, retailers or marketplaces - know they will be held to account.
Sue Davies, Which? Head of Consumer Policy, said:
“It’s really worrying that online marketplaces and popular health retailers are promoting misleading health supplements.
“Not only does this make it impossible for shoppers to trust the claims they see online but it also means people could be wasting their hard-earned cash on products which just don’t live up to the claims.
“Better oversight of the industry is desperately needed so the government and regulators can crack down on these misleading listings and ensure that any sellers who break the rules are properly held to account.”
-ENDS-
Notes to editors
Listen to the recent Which? podcast on weight-loss supplements here. The consumer champion will also be hosting a live podcast on 22nd January discussing ‘can we get healthier as we age?’
About the research
In November and December 2025, Which? looked at online product listings of food supplements across a range of popular retailers, including online marketplaces.
Which? compared claims on the product listings to approved and on-hold claims for each of the active ingredients listed, ASA rules and guidance, and general principles agreed between certain EU Member States (including the UK pre-Brexit).
Right of replies
A government spokesperson said: “Food labels must be easy to understand, accurate and honest.
“Any claims about the health benefits or nutritional value of supplements need to be backed by science and officially approved by authorities. “Companies that break these rules may be subject to enforcement action by local authorities.”
An Amazon spokesperson said: “We require all products offered in our store to comply with applicable laws, regulations and Amazon policies.
“We develop innovative tools to prevent unsafe products from being listed. We continuously monitor our store, and we take action to maintain a safe selection for our customers, including removing noncompliant products, and outreach to sellers, manufacturers, and government agencies for additional information, when appropriate.
“We have removed the highlighted products in question.”
An ASA spokesperson said: “Our rules are clear that ads mustn’t make unauthorised health, medical or weight-loss claims. In particular, ads can’t claim or imply that a food supplement can provide effects associated with prescription-only weight loss medicines.
“We recognise that these kinds of ads can target potentially vulnerable people who may be concerned about their weight or health. We’ve been using our AI-powered Active Ad Monitoring system to proactively monitor supplement ads. This has enabled us to identify and ban a number of ads that have broken our rules, including several ads for ‘faux-zempic’ supplements that misleadingly claimed to produce effects similar to prescription-only weight-loss medicines.”
A spokesperson for Coolkin said: “Our products are certified before they are put on the shelves. There is no problem.”
An eBay spokesperson said: “Consumer safety is a top priority for eBay. We have reviewed the listings identified by Which? and have removed all items that are against eBay policy.
“We use enforcement measures to help prevent unsafe items from being listed on eBay. These include seller compliance audits, block-filter algorithms, AI-supported monitoring by in-house specialists, and close partnerships with regulators. These measures help prevent millions of potentially unsafe items from being listed each year.”
Holland and Barrett said: “We are committed to providing high-quality, science-backed products that reflect the latest guidance. Product categorisation is intended to support customers to navigate our website, and we regularly carry out detailed reviews led by our science and regulatory teams to ensure this is consistent and helpful.
“Following our latest review, the H&B Acai Berry tablets now sit within our Superfood category.”
An Internal Youth spokesperson said: ‘We have passed on your points to our marketing department who will be addressing each concern and actioning anything deemed inappropriate on our product listing immediately.’
Lynda Scammell, head of borderline products at the Medicines Healthcare products Regulatory Agency said: “If a product offered as a food supplement contains medicinal ingredients or makes medicinal claims to treat or prevent disease, it will be considered a medicine and regulated under medicines law.’
“Any weight loss product which is presented in a way that is typical of authorised medicines, or which has a product name which is similar to the name of a prescription medicine to the extent that it may cause confusion in the mind of the average UK citizen is not permitted.”
A Pharmaslim spokesperson said: “The product is manufactured in the UK in a licensed facility and is a food supplement, not a medicinal product. We do not make medical or therapeutic claims for it. For completeness, the listing you are referring to is not currently active, as the product is out of stock. We are reviewing the points you raise regarding product naming and marketing presentation.”
A spokesperson for Superdrug said: “Our customers’ health and wellbeing is always a priority. Superdrug Marketplace is a curated platform where third-party sellers must adhere to strict listing guidelines, including alignment with UK health authority recommendations. We do not intend to make unjustified health claims, and any categorisation on our website is designed to help customers navigate products rather than imply specific health outcomes.
“Upon being made aware of Which?’s findings, we have paused all retailing of the highlighted product. We have also reviewed the category in question, and will take further action where necessary to ensure our content remains compliant and clear for customers.”
A Temu spokesperson said: “After receiving the inquiry, we immediately removed the products listed in the report pending further review and are working with the sellers involved to rectify their descriptions.
“Temu maintains strict requirements for dietary supplements, requiring documentation such as HACCP certification and composition reports.
“Following ASA's advice on food supplements, Temu has been enforcing and will further enhance its review process. We are also providing additional compliance training to remind sellers of their obligations to meet the required regulatory standards.”
Formula Max and Pslalae did not respond to Which?’s requests for comment.
About Which?
Which? is the UK’s consumer champion, empowering people to make confident choices and demand better. Through our research, investigations and product testing, we provide trusted insight and expert recommendations on the issues that matter most to consumers.
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