Ofcom has summoned ITV to a meeting after it ruled an episode of Alan Titchmarsh's chat show gave excessive plugs to WeightWatchers.
The report upheld a viewer complaint about an interview with actress Patsy Kensit which included several mentions of the diet firm she is paid to endorse.
Ofcom has asked ITV 'to discuss its compliance in this area' following the ruling on the five-minute interview, of which more than half was about Kensit's weight.
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Complaint: Ofcom has rapped ITV bosses after Patsy Kensit plugged WeightWatchers while appearing on the Alan Titchmarsh Show (pictured) in February
Unchallenged: Ofcom said the actress's remarks were not countered by host Titchmarsh
Broke rules: Patsy on the show in February
ITV said the actress's remarks were 'brief and not unduly prominent', but Ofcom said Titchmarsh did not challenge her claims or make mention that Kensit is a 'weight loss ambassador' for the diet company.
The media watchdog added that references to the weight loss firm were 'promotional and unduly prominent'.
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Speaking about the company, Kensit said that during filming of the soap Emmerdale, it was the only thing that 'worked' for her when managing her weight.
'I could eat whatever I wanted and wake up - you know everything,' she said. 'I was like - cause I love food.
'This way, it's a healthy way. I've got two gorgeous sons and I cook a lot and we have an evening meal together and I'm not there drinking some goop.'
The 45-year-old mother of two went on to mention the firm's ProPoints scheme twice.
Britain's Got Talent judge Amanda Holden (left) and singer Dannii Minogue (right) have been accused of using ITV's daytime shows to plug products they endorse
ITV came under fire from Ofcom two months ago after the Australian singer Dannii Minogue promoted a brand of milk, with which she has a commercial arrangement, on morning show Lorraine.
In another breach, the Britain's Got Talent judge Amanda Holden plugged a group of law firms, QualitySolicitors, on ITV's This Morning.
The watchdog said: 'Its area of business had no obvious link to her entertainment career.'
Face of a major brand: Patsy Kensit is paid to promote WeightWatchers