Half of us are now too fat and, experts warn, we're running huge risks of heart disease, diabetes and cancer

In 10 years obesity will be a bigger killer than smoking. It will be the number one cause of preventable death through heart disease, diabetes and cancer. The problem is that Britons – and especially children – are getting larger and larger.

In 10 years obesity will be a bigger killer than smoking. It will be the number one cause of preventable death through heart disease, diabetes and cancer. The problem is that Britons – and especially children – are getting larger and larger.

Now a powerful committee of MPs has launched a major inquiry into why half of us are overweight and one in five medically obese, and what can be done about it.

The Commons Health Select Committee is particularly worried about the increasing numbers of children who are grossly overweight. The latest research shows that the number of pre-school children who are overweight or obese has doubled in the last decade.

MPs will also look into claims that young people lead an increasingly sedentary lifestyle – keener to play on computers and watch television than to take exercise – and that this has contributed to levels of obesity.

Committee chairman David Hinchliffe has already received a number of submissions from expert witnesses.

By this summer, the committee hopes to have built up a picture of the true scale of the health implications of obesity – the cost to individuals, the NHS and employers. It will look in particular at whether people from different gender, social and ethnic groups are more likely to become obese, and will make international comparisons.

MPs will study the causes of the problem – diet, lifestyle and leisure. And they will seek possible solutions, such as controlling the marketing of food by retailers, educating people about the risks of obesity, promoting exercise and urging lifestyle changes.

They are also expected to examine whether the Health Secretary, Alan Milburn, and his Cabinet colleagues should be doing more to stem the rise of obesity.

"There is a growing awareness of the seriousness of the problem and the fact that it is going to be a crucial health issue in the future," Mr Hinchliffe said. "It will cost the nation a huge amount of money.

"Within Government there is already a welcome for the fact that we are looking at this. Ministers are anxious to co-operate because they recognise it to be a major problem."

Current research blames the enormous social changes over the past 50 years. Television, computers, processed food, celebrity culture and the breakdown of family life have all contributed towards the emergence of a generation of children who eat badly and don't exercise.

"There's been a huge change in the provision of food and in eating habits," said Carol Matta, a spokeswoman for the British Dietetic Association (BDA). "People of any age become overweight or obese because of differences in energy balance – either they eat or drink more energy than their body requires or it is due to low levels of physical activity."

According to the BDA only 55 per cent of boys and 39 per cent of girls exercise for the recommended one hour a day. Twenty per cent of children sit for more than five hours a day after they have been to school. Census figures point to what they are doing – four out of five children in England, Wales and Northern Ireland in 2000 had access to a home computer.

The television presenter Vanessa Feltz, who publicly battled with her "morbid obesity", says the solution is not to diet.

"Education is the key," she says. "Most fundamentally, that good, old-fashioned subject, domestic science. Nutrition, meal planning, how to feed a family a balanced diet on a budget and plan simple recipes with never an E number in sight. If our kids can't cook, they'll never learn how and what to eat."

Dr Toni Steer, a nutritionist at the Medical Research Council in Cambridge, says that children are not necessarily eating more today than they were 50 years ago, but more of their energy intake comes from sugary foods rather than starchy ones such as potatoes. And whereas vitamin C used to be obtained from fresh fruit and veg, now it comes from soft drinks.

Research by the YWCA shows that one in three girls aged 11 is overweight. The women's organisation blames poverty, because people on low incomes tend towards a fast-food diet, and the pressure for young girls to be thin, which leads them to crash diets and then binge eating. It also makes a connection with fears over safety – between 1986 and 1996 the proportion of under-17s walking to school fell from 59 to 49 per cent, while the number of car journeys to school almost doubled.

The breakdown in family life means that more than 32 per cent of children choose their own meals, according to research by Kellogg's, which is partnering the BDA in a three-year Weight Wise obesity awareness campaign.

Class of 1953

Diet: bread, potatoes, cereal, milk, red meat, fresh fruit and vegetables

Meal: roast beef, Yorkshire pudding, roast potatoes, carrots and cabbage, apple pie and custard

Main source of carbohydrates: potatoes

Main source of vitamin C: fresh fruit

Leisure: limited television with just one channel, cinema, outdoor games such as skipping, hopscotch, ball games, spinning tops and hoops

Transport: walking, cycling

Obesity: negligible

Source: Medical Research Council


Diet: processed foods and ready meals, chocolate, crisps, poultry, soft drinks

Meal: chicken tikka masala, pizza, burger, chips, mango sorbet

Main source of carbohydrate: sugar

Main source of vitamin C: soft drinks

Leisure: TV, computer games, internet, music

Transport: The number of children driven to school has doubled while the number walking to school is down to 49 per cent

Obesity: almost one-third are overweight, 10 per cent are obese