A weight-loss product advert featuring a bikini-clad model asking "Are you beach body ready?" was not offensive or irresponsible, the watchdog has ruled.
The Advertising Standards Authority received 378 complaints that the Protein World poster implied other body shapes were inferior.
The ads were defaced in Tube stations and a petition called for its banning.
However, the campaign had already been pulled over concerns that its health claims did not have EU authorisation.
The ASA began receiving the first of the complaints just after it banned the advert in April.
The watchdog was also asked to investigate whether the image used was socially irresponsible in the context of a campaign for a slimming product.
Protein World said it did not consider that the poster implied that people should look like the model or that the text and image were irresponsible.
Its intention, the company said, was to invite consumers to consider whether they were in the shape they wanted to be in.
The company said the model in the advert used the company's products.
In its ruling, the ASA said the term "beach body" could also carry a broader meaning of "feeling sufficiently comfortable and confident with one's physical appearance to wear swimwear in a public environment".
"We considered the claim... prompted readers to think about whether they were in the shape they wanted to be for the summer and we did not consider that the accompanying image implied that a different body shape to that shown was not good enough or was inferior."
The eating disorders charity Beat said the ruling was "extremely disappointing".
Spokeswoman Rebecca Field said: "While we recognise advertising and the media cannot cause eating disorders... we are aware how toxic images can be to an individual."