By Tulip Mazumdar
Newsbeat health reporter
Doctors have told Newsbeat they are worried about a "sinister" new diet patch that specifically targets young women and teenagers who don't need to lose weight.
The adverts for the Pink Patch are plastered all over websites including Facebook and Hotmail. They're a small inch-squared patch which you stick to your skin for 24 hours at a time.
The company claims it works by using natural appetite suppressants which are absorbed through the skin and make you less hungry.
But Newsbeat has received a number of texts saying the patches do not actually work.
On Facebook, the ads have been popping up on the left hand side of users pages. The caption reads: "The Pink Patch will help you lose that stubborn stone and be your skinniest."
When you click through to their website you're greeted by lots of washboard flat stomachs in tight jeans.
Some of the girls look as young as 14. Stuck to their arm or tummy is the small Pink Patch and all over the page are headlines like 'How to Be the Envy of Every Girl You Know'.
The Pink Patch ads pop up on the left of Facebook pages
23-year-old Holly Melia saw the ad on her Facebook page and says looking at the girls made her feel like "that's the way I should look... I mean my jeans don't fit me the way their jeans fit them. They've got no bits that hang over".
Holly sent off for the so called "free" week's supply of the patches. But she said they made absolutely no difference to her weight. She is a healthy size 12.
'No weight loss'
Other people who texted Newsbeat said they ended up spending up to £80 on supplies of the patches they didn't want because the company kept sending packs even when they hadn't asked for them.
The small print on the website does say you have to cancel your subscription.
Dr David Haslam is from the National Obesity Forum. He speaks for their 4000 members including doctors, nurses and dieticians.
He said: "This is purely done to make money without any thought about the effect it's having on these vulnerable teenagers with image problems who think they need to lose weight but they don't."
Dr Haslam says advertising this way is dangerous
He adds there's "no convincing clinical evidence" that any of the natural ingredients like a seaweed called Fucus Vesiculosus , or "Bladderwrack" actually help with weight loss.
He goes on to warn the company: "stop advertising in this way... It's dangerous because eating disorders are increasingly common... We hear about the size zero debate etc raising awareness of weight problems, like anorexia.. And this is just blatantly promoting it [eating disorders]."
Susan Ringwood from Eating Disorders charity BEAT said: "The look of the website, the graphics used [of the girls] are directed much more towards younger teenagers and to pray on their concerns about their body image is particular dangerous."
The company which is called CYC Marketing is registered in the UK but based in the US. That is where the patches are made. A spokesperson said the company does follow The Food and Drug administration's manufacturing guidelines.
They go onto say "we believe that customers are very pleased with the results they achieve".
They also point out: "the Company's website clearly states that products are not for use by anyone under age 18."