A report published by the government predicts more than 12m adults and one million children will be obese by 2010 if nothing is done.
Obesity levels could see a massive increase
The Health Survey for England also warns 19% of boys and 22% of girls aged two to 15 will be obese.
The figures would mean the government would fail to meet its target to halt the rise in childhood obesity.
The report also says having two obese parents means children have five times the risk of being obese themselves.
Health experts say a range of short and long-term measures are needed to reverse the rise in obesity.
MAURA GILLESPIE, BRITISH HEART FOUNDATION
"We are demanding the government place restrictions on advertising junk food
to children before the 9pm watershed - a policy that can only have a positive
impact on young people's attitudes to foods high in fat, sugar and salt.
"These figures are of no surprise to us - we are rapidly becoming a nation
bursting at the seams.
"We are all going to have to work together to curb these figures and the risk
to our nation's health.
"The government is rightly touting the Small Change, Big Difference agenda as
part of the solution - inspiring people to make individual changes which
together could make a big difference to the obesity crisis.
"But the government must deliver the big changes that we need for real
difference to be achieved."
ANDREA LANE, STROKE ASSOCIATON
"These obesity figures cast a worrying shadow over the future health of the nation, particularly the increased risk factors for major health concerns like stroke - the UK's third biggest killer.
"Eating a balanced diet and taking regular exercise part of a healthy, active lifestyle can all help to control weight and reduce the risk of stroke.
"Even making small changes like cutting back on salt at mealtimes can have a positive effect on health by helping to reduce blood pressure."
DOUGLAS SMALLWOOD, DIABETES UK
"Not all people with diabetes are overweight, but at diagnosis 80% of those diagnosed with type 2
diabetes were overweight.
"If obesity rates continue to rise at such a rapid rate, the number of deaths
due to diabetes will increase in line with this.
"The World Health Organization has already predicted a 25% increase in deaths
caused by diabetes over the next decade.
"This is not to mention the blindness, amputations and strokes which the
condition can also lead to.
"We're delighted to see the commitment voiced by the government on tackling
this huge problem. But we want to see these words turned into actions."
TAM FRY, NATIONAL OBESITY FORUM
"The obesity figures announced today are tragic but no-one should be surprised by them.
"The government has been announcing for years what needs to be done to fight the nation's fat - but then has done very little to achieve it.
"It may have played around with a few initiatives but real action is still not yet apparent.
"If today's announcement does finally commit to improving the 'obesogenic' environment we live in, then, and only then, will individuals have a real chance of improving their lifestyles in the way that government desires.
"We welcome today's emphasis on the need to protect children from obesity and particularly young girls.
"The government has admitted that it is 'off course' to achieve its target to halt the year-on-year rise of obesity in children under 11 years by 2010. Time is fast running out to get back on track. The government cannot afford not to."
DR SUSAN JEBB, MEDICAL RESEARCH COUNCIL NUTRITIONIST
Dr Susan Jebb, Medical Research Council nutritionist, said: "The government's bid to halt the rise in childhood obesity by the end of the decade had always been an unrealistic target.
"We know there has been an inexorable trend where obesity rates have gone up, so it's not surprising that these figures show its going to continue going up.
She said it could take many decades to reverse the trend.
"People are not thin one day and fat the next, or vice versa."
But Dr Jebb said there were things people could do now.
She said parents needed to focus on making healthy diet and activity choices for themselves, and particularly for their children.
"People have got to start to make healthy choices. A lot of what people do in their own lives isn't helpful."
She said helping children develop healthy lifestyles was key.
"Prevention is much easier than losing weight. It is easier to stop people gaining weight than to treat them when they have put weight on."
JULIAN HUNT, FOOD AND DRINK FEDERATION
"The government has rightly made obesity a public health priority.
"But there is no silver bullet that can be fired at this problem. It will only be resolved by encouraging consumers to make sensible lifestyle choices.
"This is something about which both industry and government agree.
"Whilst food is only one factor in an extremely complex situation, industry is committed to continuing to work with government to help create a society of informed consumers.
"But a key part of any programme to effect lifestyle change is getting people to understand that they need to balance the calories they take in with the calories they expend through exercise."
RICHARD WATTS, CHILDREN'S FOOD BILL CAMPAIGN
"Obesity has become the nation's number one public health problem. We're not going to solve
it by half measures.
"The government needs to go further and faster to improve people's diets by protecting children from junk food adverts, making traffic-light labelling compulsory and putting cooking back in the National Curriculum.
"Progress on these fronts is so slow because the Government seems determined not to upset the powerful food industry.
"The time has come to stop pussy-footing about and take the urgent action we