Major retailers and online marketplaces are employing "misleading" claims to advertise weight-loss supplements, a consumer watchdog has warned. Which? revealed it found evidence of Amazon, eBay, Holland & Barrett, Superdrug, and Temu, among others, making "outlandish claims" to market these products, with little enforcement of existing rules to curb such practices.

Companies are legally prohibited from making health claims about a product without sufficient evidence to support them. The Department of Health and Social Care (DHSC) maintains a health claims register, which explicitly details what businesses can – and cannot – state an ingredient can do for people’s health, often with specific wording and conditions for its use.

The watchdog found Extreme Burn supplements by a business called Formula Max 5 listed on eBay, carrying the claim that 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”.

A number 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 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 did not make any weight loss claims.

At Holland & Barrett, Acai Berry tablets were listed under the “fat burner” section of the website, even though the page and packaging for the product made no such claims.

Superdrug’s “appetite suppressant” section included a cinnamon supplement which made no such claims of its own.

Which? said it also saw products listed for sale on online marketplaces which made unfounded claims to target certain areas of the body or be as effective as weight-loss jabs.

The Advertising Standards Authority (ASA) states that products cannot say how much weight customers could lose or how quickly, or from which part of the body, as this was something brands could not predict.

Which? said it also saw products listed for sale on online marketplaces which made unfounded claims to target certain areas of the body or be as effective as weight-loss jabs (Getty/iStock)

Which? found a “keto fat burner” supplement from the brand Pslalae on Temu claiming 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, suggested 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 allowed to claim that they can have the same effects as prescription medicines, such as weight-loss jabs.

However, Which? found a listing for Phentramine 375 by Pharmaslim on eBay which read: “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?”

Which? said it reported all its findings to the retailers, which it claimed had led to more than 50 “misleading” weight-loss supplement listings being taken down.

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.”

A Government spokesman 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 spokesman said: “We require all products offered in our store to comply with applicable laws, regulations and Amazon policies.

“We have removed the highlighted products in question.”

An ASA spokeswoman 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.”

Coolkin told Which?: “Our products are certified before they are put on the shelves. There is no problem.”

An eBay spokeswoman 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.”

Holland and Barrett said: “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.”

A Pharmaslim spokesman 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.”

Superdrug said: “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.”

Temu 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.”