A band of anti-fat vigilantes is reportedly on the loose in London, shaming those who are overweight in brazen attacks that experts have denounced as outrageous and futile.

Calling themselves ‘Overweight Haters Ltd’, members of the group have given derogatory cards to women who are rotund, labelling anyone who loves them “perverted”.

The obesity epidemic is raging, both in the UK where the vigilante group is operating, and in Australia, where the rising number (63 per cent) of overweight people could be at risk of similar insults.

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An alleged victim, health worker Kara Florish, 30, from Essex, described the printed card she received while sitting on a train as “hateful and cowardly”.

“I am not upset myself, I am smaller than the national average and not exactly obese, but this is hateful and cowardly and could potentially upset people struggling with confidence and eating disorders,” Ms Florish posted on Twitter.

London police have reportedly launched an investigation into the incidents, The Guardian reported.

Author and journalist Sean Thomas Knox claimed to have witnessed another incident, again involving an overweight female. He described the man who gave her the card as a ‘bearded hipster’ who was ‘smartly, trendily dressed’.

“Young man just got on train at Oxford Circus, gave printed card saying YOU’RE FAT to overweight girl. He jumped off. She read it and cried,” Mr Knox posted to Twitter.

“Her stunned, desolate reaction was very real. Then tears.”

An Australian body image expert slammed the incidents as “completely unacceptable behaviour”.

“I can’t believe these sorts of things happen, it is almost incredible,” University of South Australia body image expert Professor Tim Olds said.

The same card appears to have been used in both incidents. It reads:

“Our organisation hates and resents fat people. We object to the enormous amount of food resources you consume while half the world starves. We disapprove of your wasting NHS money to treat your selfish greed.

“And we do not understand why you fail to grasp that by eating less you will be better off, slimmer, happy and find a partner who is not a perverted chubby-lover, or even find a partner at all.

“We also object that the beautiful pig is used as an insult. You are not a pig. You are a fat, ugly human.”

Fat shaming ‘has the opposite effect’

It is “absolutely not helpful” to shame those who are overweight as this can exacerbate their health issues, according to the body image expert.

“It is absolutely disgusting and it is completely unacceptable to say things like that,” Professor Olds said.

“It is completely and totally counterproductive.

“It is going to make these people withdraw even more: already they feel ostracised in society and already they’re reluctant to go swimming, to get undressed in locker rooms and so forth.

“They are much more likely to go into their shell and are much more likely to seek comfort in food.

“This is going to make it much much worse.”

-with Jackson Stiles and Anthony Colangelo