The Government has defied calls to outlaw junk-food advertising despite coming under growing pressure to impose a ban to combat Britain's "obesity crisis".
Patricia Hewitt, the health secretary, played down demands for a ban and warned that any such move could jeopardise children's television programming.
She also raised doubts that the proposed 9pm watershed on ads would work, saying that many children watched TV after that.
Her remarks were much cooler on a ban than the strong warning to the advertising and food industries issued by the prime minister, Tony Blair, in July. Hewitt's words suggest the Cabinet remains opposed to statutory curbs and hopes the review by Ofcom will resolve the issue.
Pressure for government action intensified after the Department of Health published research predicting that three in four men and three in five women would be overweight or obese by 2010. The number of men suffering from obesity would rise from 4.3 million in 2003 to 6.6 million by the end of the decade and the number of women from 4.7 million to 6 million, the DoH forecast.
Groups including the National Obesity Forum and the British Heart Foundation said the figures showed the need for more drastic action than a voluntary approach.
But Hewitt replied cautiously, saying the evidence about the influence of food ads on children and parents was "mixed". She added that Ofcom and the Government would have to assess the potential impact of a ban on certain foods.
She asked: "What effect would a ban on advertising certain foods actually have on the foods children are eating, remembering, of course, that a lot of programmes children watch don't fall within the watershed where an advertising ban would take effect?"
The health secretary added: "We need certainly to look at the impact on broadcasting and whether that would actually damage children's television programming, which is in itself extremely important. We need to balance these different things and then make a judgment."
Hewitt suggested that people should take responsibility for their health rather than rely on the Government. "We have already stepped in to try to slow this worrying trend down, but there's only so much the Government can do," she said.