The controversial ad campaign featuring a model in a bikini that asks “Are you beach body ready?” has been banned by the advertising watchdog because of “concerns” over its weight loss claims.

After receiving about 360 complaints about the campaign, mostly that it objectified women, the Advertising Standards Authority has also launched an inquiry into whether the ad is offensive.

A spokesman for the ASA explained that it was the health claims that led to the decision not to let the ad return in its current form. “We’ve met with Protein World to discuss its “Are you beach body ready?” ad campaign. It’s coming down in the next three days and, due to our concerns about a range of health and weight loss claims made in the ad, it can’t appear again in its current form.”

The ad campaign, which promotes Protein World weight-loss products, is due to end a three-week run on London underground. The vast majority of complainants argue that the ad is offensive, irresponsible and harmful because it promotes an unhealthy body image.

“Although the ad won’t appear in the meantime, we’ve launched an investigation to establish if it breaks harm and offence rules or is socially irresponsible,” said the spokesman.

“We will now carefully and objectively explore the complaints that have prompted concerns around body confidence and promptly publish our findings.”

Representatives of the ASA met with the company on Wednesday to discuss the nature of the complaints.

The ASA will investigate the ads to see if they are in breach of the UK code relating to taste, decency and harm and offence.

Transport for London is in the process of removing the ads because they have come to the end of their contract period.

“It is coming to a natural end,” said a spokesman for TfL. “This advertisement will begin to be removed from our network as scheduled from tomorrow. We have received one complaint about it and we will be guided by the Committee of Advertising Practice and Advertising Standards Authority if a similar advert were to be submitted again. We have zero tolerance towards graffiti on the network and take action to prevent it and remove it.”

The campaign has touched a nerve, with almost 60,000 people signing an online petition at Change.org calling on Protein World to take down the ads.

A “taking back the beach” protest has been organised to take place in London’s Hyde Park on Saturday. More than 400 people are expected to attend.

Protein World, which has received death threats about the campaign, has been unrepentant with chief executive Arjun Seth likening feminists to “terrorists”.

Katie Hopkins called the protesters “angry chubsters” on Twitter – a comment that prompted Protein World’s head of marketing to say it was “great” that the columnist had got involved.

This month, the ASA investigated nine issues regarding Protein World’s website and upheld all of them. Questions had been raised over whether a number of health and nutrition claims were authorised on the EU Register, and a competition featured before and after photographs which implied a rate of weight loss.

