People must take more responsibility for their health to relieve pressure on the NHS, Tony Blair has said.
The prime minister said, in a speech, it was the job of ministers to "empower the individual, rather than command".
Speaking in Nottingham, he said that unless the food industry agreed to limit junk food adverts to children by 2007 he would bring in mandatory rules.
The prime minister was forced to pause briefly as a heckler shouting about the "war on terror" interrupted him.
The person, who took off his top to reveal slogans including the words "Iraq War still illegal" and "Impeach Tony Blair", was quickly removed from the audience.
Under the banner "Our Nation's Future", and behind a rostrum carrying the labels HM Government and Boots, Mr Blair's key message was that the NHS could be crippled by the cost of treating people affected by obesity, alcohol abuse and smoking.
He said that failure to address bad lifestyles was putting an "increasing strain" on the health service, and was hindering efforts to outlaw social inequalities.
"Ten per cent of NHS resources today are used to treat diabetes," he said. "By 2010 the estimate is that this could double.
"That's 20 per cent of the entire resources of the NHS - and it's avoidable. Three quarters of diabetics are Type 2 diabetics, and two thirds of them have a disease which could be preventable with exercise, diet and more healthy choices."
Health care could not just be about treating the sick, but helping people to live healthily, which required commitment from individuals, companies and the government, he said.
Labour has "explicitly" abandoned the "paternalistic state of the post-war years, not because that state did not fulfil a worthwhile task, but simply because such a state no longer fits the times", he said.
But the truth was everyone paid the price "for the failure to take shared responsibility".
"That doesn't mean you stop treating people on the NHS who smoke, or force people to do things that they don't choose in their lifestyle," he said.
"But it does mean that government has to play an active role in precisely the way the enabling state should work and that is empowering people, setting the conditions in which they can choose responsibly."
He argued that public health problems were "not, strictly speaking, public health problems at all".
"They are questions of individual lifestyle - obesity, smoking, alcohol abuse, diabetes, sexually transmitted disease," said Mr Blair.
"These are not epidemics in the epidemiological sense - they are the result of millions of individual decisions, at millions of points in time."
Child seat belts
The prime minister conceded that there was a difficult balance to be struck between the state being seen as over-bearing and the introduction of sensible measures that could save lives.
He said measures such as making seatbelt wearing compulsory, and making medicine bottles child-proof, had proved worthwhile.
Dr Mike Knapton, director of prevention and care at the British Heart Foundation, welcomed Mr Blair's focus on prevention of illness.
But he stressed that health problems were not just down to individual lifestyles.
"If millions of children are not eating the right food and not getting enough exercise then it's not just a million individual problems, it's a collective problem that will require us all to work together, including government," he said.
"Requiring the food industry to adopt one sensible system for front pack labels and banning junk food advertising before the watershed would be a good next step."
Cathy Moulton, care adviser at Diabetes UK, echoed the call for better food labelling, adding that junk food advertising to children should be banned now and people encouraged to take more exercise.
"As obesity increases we are seeing more and more young people, some as young as seven, being diagnosed with Type 2 diabetes, previously only seen in those over 40," she said.
"It won't be long before we start seeing our children growing up losing limbs and becoming blind as they develop the serious complications of having the condition."