Pupils should begin school with an 8 o'clock breakfast club and remain until 5.45pm, Barry Gardiner, Labour MP for Brent North, told the House of Commons health select committee.
The extended day would allow time for physical activities ranging from boxercise and ethnic dance to traditional sports such as netball and rugby, Mr Gardiner said.
It would also reduce the time young people spend unsupervised "hanging around" in town centres, when they are most likely to engage in criminal activity.
Teachers would be expected to work throughout the day but would be guaranteed two hours for preparation and assessment while pupils were taught sport by qualified coaches.
A pilot project in Mr Gardiner's constituency offering pupils an extra two hours PE per week has been praised by Downing Street officials. Mr Gardiner told The TES that teachers would be paid for the extra hours worked at a rate to be negotiated between unions, employers and the Government.
"The Government's target of two hours PE each week is not enough if we are to tackle childhood obesity.
"This proposal would be a winner for kids, a winner for government and a winner for teachers because they would be paid for doing work they currently do in their own time at home," he said.
Mr Gardiner was giving evidence to the Health committee's inquiry into obesity.
He has written to the teaching unions to arrange a meeting to discuss his ideas.
John Bangs, National Union of Teachers head of education, said: "We do need to look at the place of PE in the curriculum but this must be done with existing PE departments rather than as an add-on.
"If extending the school day means extending teachers hours then there could be some real problems, even if they are paid for the additional time."
International league tables show that the UK is one of the fattest countries in Europe.
One in 10 six-year-olds and one in six 15-year-olds is classed as obese and the rate is rising faster than anywhere else in the developed world.
The National Audit Office has warned that if present trends continue, by 2025, the cost of treating diabetes will be as much as the NHS currently spends on all treatment.