"Are you beach body ready?"
These bold black letters - against a bright yellow background and a tanned, bikini-clad model - have sparked fury.
The ads first appeared in the London Underground and they have been annoying commuters ever since.
Thousands have spoken out against the 'sexist' nature of the Protein World promotion and the company's Twitter feed has been inundated with complaints.
Some critics have even taken matters into their own hands, scrawling messages of body positivity across the images instead.
Now more than 40,000 people have signed a Change.org petition calling for the adverts to be removed.
Charlotte Baring, from East Sussex, the petition reads: "Protein World is directly targeting individuals, aiming to make them feel physically inferior to the unrealistic body image of the bronzed model, in order to sell their product.
"Perhaps not everyone's priority is having a 'beach body' (by the way, what is that?), and making somebody feel guilty for not prioritising it by questioning their personal choices is a step too far.
"A body's function is far more intricate and important than looking 'beach ready', so in fact it is Protein World who have confused their priorities, if anyone."
And bloggers Fiona Longmuir and Tara Costello, who posed in their bikinis in front of the glaring sign before posting their thoughts on Twitter, have arranged a huge event called 'Taking back the beach'.
Meeting in Hyde Park on May 4, the girls are encouraging men and women of all shapes and sizes to get together for massive version of the photo.
A Facebook page was also created for the hashtag #eachbodysready
May Gibbs, one of the individuals behind the Facebook page, said: "We know there is no 'ideal' body. Everyone is different and everyone's bodies are ready when they say they are.
“The beach should be for fun and relaxation, not judgement and comparison. It is a reminder to advertisers that the public cares, and will be heard on these issues.”
Protein World has denied accusations of sexism.
In a statement, a spokesperson said: "It is a shame that in 2015 there are still a minority who aren't focusing on celebrating those who aspire to be healthier, fitter and stronger.
"Renee, our stunning model, falls well within what the British Government deem to be a healthy weight, based on the BMI system.
"We now run Britain’s largest protein facility, selling our products in over 50 countries to more than 300,000 customers. Most of them are women. How could we possibly be sexist?
"Getting 'beach ready' is not a new concept. It's a fashion that is followed by millions (admittedly not everybody as we have seen!) around the world when they look forward to their summer holiday. We absolutely have no intention of removing the adverts because of a minority making a lot of noise."
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