There is a growing sense of unease among broadcast advertising officials about the Nutrient Profiling Model (NPM) underpinning Ofcom's ban on advertising junk food to under-16s.

At a key industry seminar this week, which was attended by The Grocer, those charged with enforcing Ofcom's new regime appeared less than enamoured with the NPM developed for Ofcom by the Food Standards Agency.

The whole tenor of the seminar suggested even the code's enforcers themselves didn't believe the advertising ban would help significantly to reduce obesity - and in some speakers even sounded apologetic.

Peter Johnson, copy group manager of the Broadcast Advertising Clearance Centre, spoke of his sympathy for food brands. "We think television advertising is an easy target and are sympathetic to those who say that there are no good or bad foods, only good and bad diets and lifestyles."

However, broadcasting officials hammered home to brand owners that they were "stuck" with the model at least until January 2008.

Shahriar Coupal, code policy manager for the Committee on Advertising Practice, told delegates he understood the model was still being debated.

But he said: "We're not going to continue that debate today. Nutrient Profiling will not be reviewed until 2008."

A source close to Ofcom admitted to The Grocer this week that the scheme wasn't perfect. "Ofcom said it would need some means of identifying high fat, salt and sugar foods, and the FSA said it should be the one to develop a scheme. It is still the only game in town. Several times, Ofcom has said it would be happy to look at alternatives, but the FSA one is all it's got".

Meanwhile, Sainsbury's chief executive Justin King this week condemned the model for causing confusion among consumers.

He criticised the use of a 100g portion to gauge whether a food is high in fat, salt or sugar, arguing that nobody would ever eat that quantity of certain foods, such as Marmite and honey - both banned from advertising.

"Because of the nature of the model, the more complex a food, the more chance it has of passing," he said. "Meanwhile whole, individual foods often don't stand a chance.

"The ad ban means customers find it difficult to know what the message is. Some foods they perceived to be bad are good, and others they thought were good, are bad.

"There is no such thing as a bad food, just bad diets," he said. "We are not supporters of the model."

The Grocer continues to gather high-profile support for its Weigh It Up! campaign, which aims to persuade Ofcom to rethink the model.

Liberal Democrat shadow secretary of state for health Norman Lamb said he had written to Ed Richards, chief executive of Ofcom, to outline his support for our campaign.

We have also recruited the British Beekeepers' Association, which boasts 10,000 members. Dismayed at the vilification of honey by the ban, president Dr Ivor Davis said: "It would be a tragedy if the proposals classified honey as unhealthy."