Privately, the culture secretary knows well enough that outlawing such ads on TV would be no more than a symbolic act that is unlikely to do anything to reduce burgeoning levels of obesity. But Jowell is also a politician who is only too aware of how effective lobby groups have been in fuelling demands for a ban. The fact that this would be a knee-jerk reaction to a complex problem is of little consequence. The Government can't be seen to be sitting on its hands.
Hence, her measured speech at last week's ISBA annual conference, at which she urged Britain's advertisers and their agencies to be proactive and not let those pressing for a ban win by default.
The sharper tools in the ad industry's box will have quickly cracked Jowell's lightly coded warning. "If you do nothing to show you're part of the solution rather than part of the problem, I'll not be able to hold back a growing tide of opinion demanding Government action," was the essence of her message.
In reality, though, a statutory ban would do more harm than good. This is mainly because the withdrawal of what is still a relatively modest amount spent by food and drink advertisers during children's programming would have a disproportionately large effect on the continued quality of that programming.
Also, although precise figures on total budgets for TV advertising directed at children are hard to calculate, rough estimates put it at less than £100 million a year, of which no more than 30 per cent goes on the promotion of food and drink. Moreover, no children's programme attracts an audience of more than 400,000 and the most popular are still produced by the ad-free BBC.
Jowell certainly knows all this. Less certain is how she expects the industry to respond effectively to her exhortations to focus its creative brainpower on encouraging healthy lifestyles. Sure, the upcoming European football championship and the Olympic Games present opportunities to find this out. But as Cadbury discovered with its "get active" campaign and alcohol manufacturers found with efforts to promote sensible drinking, consumers are mistrustful of finger wagging from those with vested interests.
Nobody disputes the need for the industry to play its part in tackling obesity. Consumers demand it and advertising can't be effective unless it's in tune with the prevailing public mood. Now all that remains is for Jowell to say where the money is coming from.