The advertising watchdog has banned an advert that claimed dieters could lose a stone in just two weeks by attaching a slimming patch to their bodies.
The internet advert for the Pink Patch was "irresponsible" and promoted "bad medical practice", the Advertising Standards Authority (ASA) said.
The company behind the Pink Patch claims the device works by releasing herbal ingredients into the body which promote weight loss, but the ASA said it had seen no evidence that the ingredients when combined together in the patch resulted in any weight loss.
Advocating weight loss at a rate of one stone in two weeks was "contrary to good medical and nutritional practice", the watchdog added.
The ASA code states that "claims for weight loss products should be backed by rigorous trials on people", but it was found that some of the studies for the patch were carried out on animals, rather than humans.
The ASA assessment read: "The evidence did not persuade us that wearing the Pink Patch would result in a loss of body fat and we concluded that the claim "drop a stone in two weeks" was unsubstantiated and could mislead."
Olivia Campbell, spokeswoman for the ASA, added: "The ad was irresponsible for promoting bad medical practice of losing a stone in two weeks and failed to provide persuasive scientific evidence to substantiate its claims."