Every week, the average Briton eats the very rough equivalent of a rump steak, a couple of breasts of chicken, a string of sausages, a slab of cheddar, a bowl of ice cream, a big knob of butter, five tablespoons of margarine, a quarter of a cup of oil, 20 teaspoons of sugar, a dollop of honey, a slice of fish, two eggs, a Mars bar, seven potatoes, half a box of cornflakes, a loaf of bread, two bowls of pasta, a bowl of rice, a few sprigs of broccoli, half a bag of carrots, two bananas, two apples, two oranges and a chocolate eclair. We wash that all down with a can of lager, two cans of Coke, two cans of Diet Pepsi, dozens of cups of tea and coffee, two cups of fruit juice and about two litres of milk and cream. That is not quite enough to fill us, though, so we each spend an additional pound;7.36 eating and drinking out every week.

About one in four Britons in their mid-20s is overweight. By the age of 34, this has risen to about half of the population, and in middle age to 75 per cent of men and 60 per cent of women. In retirement, women catch up with the men. In other words, the majority of us will, sooner or later, become fat. And many of us will become very fat: about 20 per cent of Britons are now classified as obese, meaning their weight is a serious threat to their health. That is about three times the level in 1980, when 8 per cent of women and 6 per cent of men were obese. A report by the National Audit Office in 2001 warned that, if current trends continued, a quarter of British adults would be obese by 2010.

If those figures are scary, prepare yourself for the real horror story. At the end of last year, chairman of the Food Standards Agency Sir John Krebs, a man not given to exaggeration, said we were sitting on a “ticking timebomb” of childhood obesity. About one in five children is overweight, three times more than the level 20 years ago, and researchers estimate that 8.5 per cent of six-year-olds and 15 per cent of 15-year-olds are clinically obese. Although some experts give a lower estimate - Jaround 5 per cent of all children - obesity is massively more prevalent among children than it was in 1984, when 0.6 per cent of boys and 1.3 per cent of girls were classified obese. Krebs warned that if nothing was done the current generation of schoolchildren would have shorter lives than their parents, the first fall in life expectancies for a century.

The cumulative effect

Dr Toni Steer, nutritionist at the Medical Research Council’s Human Nutrition Research Unit in Cambridge, urges some caution in interpreting these doom-laden prophesies: “If you look at the media headlines, you might get the impression that all children are obese. Then, you get out into the real world and have a look around and you will see that an awful lot of children are looking perfectly healthy. In fact, about 80 per cent of children are managing quite well. That might tempt you to dismiss this problem and that would be a mistake.”

Dr Steer says childhood weight gain is a serious issue because it is the beginning of a cumulative process which is difficult to reverse later in life: “If you are overweight as a child you are much more likely to be obese as an adult and the longer you are obese for, the more likely as an adult you are to develop chronic illnesses associated with obesity.”

These illnesses include Type-2 diabetes, which is traditionally associated with adulthood but has recently been appearing among schoolchildren. A study by the National Audit Office estimated that 250,000 cases of Type-2 diabetes, which reduces the life expectancy of fat people by eight years, were caused by obesity in 1998 alone. According to the same report, obesity is causing 28,000 heart attacks every year and there are significantly increased risks of suffering a stroke and developing certain types of cancer: you are three times more likely to contract cancer of the colon if you are obese. Osteoarthritis, angina, back pain and gall bladder diseases are common conditions for fat people. A young adult is 50 per cent more likely to die if they are obese than if they have a healthy body weight and about 30,000 deaths each year are due to obesity-related illness.

The epidemic is already costing the NHS more than pound;500 million a year and if the numbers affected increase to 25 per cent of adults by 2010 the total bill will be around pound;3.6 billion. By that time, obesity will have greatly outstripped smoking as the chief danger to the nation’s health.

So how do we stop it? First, we must identify the causes. According to Dr Steer, they are simple: “You will hear people talking about having a slow metabolism and such rationalisations. This kind of talk is absolute rubbish. The reason why people become overweight is because they eat too much for the energy they are expending.”

This straightforward analysis fits with the huge recent increase in obesity. If the major causes of obesity were biological factors innate to individuals, it is difficult to see how we could account for so many more of those individuals in 2004 than in 1984. But, while the general cause is simple to identify, Dr Steer admits the problem will be “devilishly difficult” to address, mainly because the factors that are causing us to overeat and underexercise are endemic in present-day society.

Dr Steer explains: “We are living in a much more obesogenic environment than we used to. In the 1970s and 1980s, how many supermarkets were open 24 hours a day? How many hours did children spend playing with computers? How many children had televisions in their rooms? How many remote controls were there? How many of us had to get up to answer the phone, rather than reach for our pocket? It sounds a small thing, but all this has kept us sitting in our seats.

“We now get in a car to go anywhere. Children are taken to school by car, rather than walking as their parents did. If you look at how eating habits have changed, people used to eat as families but now that has broken up. We are tending to eat more convenience foods and they tend to be high in fat and salt. Now children can go down to the petrol station that is selling snack bars all day and all night, but that wasn’t the case 20 years ago. It is easy to miss it, but the world has changed a lot,” says Dr Steer.

It is a world in which young people, in particular, are being targeted by food producers with sophisticated advertising campaigns urging them to eat unhealthy products. A study in 2001 by the food pressure group Sustain uncovered what it described as a “hidden world” of food advertising which is largely unnoticed by older generations. During adult viewing hours (after 9pm), food and drink accounted for 21 per cent of advertisements, but the figure leaped to 48 to 58 per cent during children’s programming.

And more than 95 per cent of those commercials were for fatty, sugary and salty products - the very foods we need to persuade children not to eat if we are going to defuse the “obesity timebomb”.

A reluctant industry

Moves just to identify sugary or fatty foods as undesirable - let alone restrict their producers’ marketing efforts - have met with formidable resistance from the industry. Last year, for instance, the sugar industry in the US threatened to lobby Washington politicians to cut funding for the World Health Organisation, if the WHO did not scrap advice published in its report Diet, Nutrition and the Prevention of Chronic Diseases that sugar should make up less than 10 per cent of any diet. Jack Winkler, director of Food and Health Research, says: “This is not the first time the sugar industry has squeezed the WHO. What was unusual was that they let this report get into the public domain. The normal way is to plant a man on the committee. They are now putting together a global strategy to implement the report. Fifty-seven countries have submitted reactions to the report and the majority have been against its findings. The industry wields huge power. You are talking about some of the world’s biggest companies - Nestle, Kraft, Unilever, Coca-Cola, Pepsi-Cola - and the raising of these issues represents a massive threat to their business.”

The industry has never been shy of wielding its power. In 1983, a groundbreaking National Advisory Committee on Nutrition Education report, which marked a long-overdue change in Britain’s public-health advice from an emphasis on food deficiencies to an acknowledgement of the problem of over-eating, had to be rewritten 13 times to mollify industry lobbyists. In 1994, a Department of Health report on nutritional aspects of cardiovascular disease raised the industry’s ire because it suggested an “illustrative healthy diet” in which the average consumer might halve soft-drink and biscuit consumption to eat more healthily. A delegation of industry executives was reported to have met ministers and civil servants to ask for a change. When that was unsuccessful, they were reported to have asked civil servants to leave the room and to have threatened to withdraw Conservative Party donations (some later did). When ministers still resisted, they leaked the report to the Daily Telegraph, which ran a story ridiculing the report’s authors for trying to regulate the British diet.

A year later, The Economist wrote that a national report on obesity had been “gutted” because of the dangers it posed to the industry. In 1997, another report was pulped after last-minute manoeuvrings over advice on an upper limit for daily consumption of red meat. The same year, the Labour Party decided not to implement targets on reducing obesity, which had been proposed earlier but were widely viewed as unrealistic. The campaign to introduce regulations to replace the relatively lax rules on food advertising, which include voluntary codes forbidding producers from promoting children’s snacks as replacements for main meals, has also foundered since a high tide of optimism when Labour came to power.

Government ministers have made it clear they are not disposed to regulate advertising by an industry that employs 500,000 people in the UK, has a turnover of pound;65 billion, exports worth pound;9 billion, and makes large donations to both main political parties.

Winkler, a veteran public-health lobbyist, says: “When I started out, my attitude was: ‘We’ve got a problem so the government ought to do something about it.’ But later I asked myself whether governments really were ever going to be part of the solution. You look at the size of the issue and what is really striking is how little governments have done, not just our own but around the world. It is not just to do with the power of the industry. From the politician’s perspective, this is a really unattractive issue. If you do anything, it looks like you are telling people how to live. Somebody once called it the ‘dictatorship of the diet’ and there are not many votes in that.”

Exercise is good for you

So, that’s it then - it’s food multinationals who are making us fat, and we are too set in our ways, and our politicians too duplicitous to save us! But Professor Neil Armstrong, director of the Children’s Health and Exercise Research Centre at Exeter University, warns against drawing a simple causal relationship between diet and weight: “If you look at the figures, children are taking in fewer calories than they were 50 or 60 years ago,” says Professor Armstrong. The average energy intake of 14 to 15-year-old boys in the 1930s was 3065 kcal (kilogram calories) per day. In the 1960s, it was 2795 kcal; in the 1970s, 2610 kcal; and in the 1980s, 2490 kcal. A similar decline has been seen in girls. More recent figures from the Government’s National Food Survey indicate that average household energy intake has been declining since the 1970s, just as obesity has begun to increase rapidly.

Some experts caution that the National Food Survey figures do not include alcohol, soft drink, or confectionery brought into homes or meals and drinks consumed outside the home. These account for about 20 per cent of average energy intake, according to recent figures - a significant increase since the 1970s. And the easy availability of high-energy junk foods may make it much easier to put on large amounts of weight. But Professor Armstrong is insistent: “I fervently believe that the obesity problem is more to do with a fall in physical activity than a problem of nutrition.”

The National Audit Office report on obesity quoted one estimate that the extra physical activity involved in living 50 years ago, compared with today, was equivalent to running a marathon every week. With wide car ownership and increased fear about potential danger to children, women and old people, walking in public spaces is much less common than it used to be. Between 1986 and 1996, for instance, the number of children walking to school fell from 59 to 49 per cent and the number of car journeys to school doubled. When we do walk, escalators, lifts and automatic doors are all designed to make it as unstrenuous an activity as possible Safety fears have made parents much less willing to allow their children to play outside the home and, at the same time, sport at school has been in decline. A study by Sport England showed that the proportion of young people spending more than two hours a week playing curricular sport decreased from 46 to 33 per cent between 1994 and 1999. Meanwhile, television, computers, videos and DVDs have greatly increased the sedentary lifestyle. The average person in England watched more than 26 hours of television a week in the mid-1990s, compared with 13 hours in the 1960s.

Many young people would not understand the concept of the “test card”, a familiar sight bygone television screens when no programmes were scheduled.

With obesity levels rocketing, should we campaign for a return of the “test card” or for a tax on computer games and unhealthy foods? Should we stop junk-food manufacturers from advertising or enlist our children into sports clubs and get ourselves cycling to work? There are almost as many solutions to obesity as there are experts, and an effective response would probably feature a combination. Politicians talk around it and newspapers trumpet gloomy forecasts, but there seems to be little action. Are we too weak willed and our leaders too duplicitous to address this major public-health crisis of the 21st century?

Jack Winkler, for one, believes things will change: “Not this round or the next but the one after that. I call myself a ‘black optimist’: this problem is going to get so huge, so many people are going to be dying and it is going to be costing our societies so much, that, eventually, something is going to have to be done.”

www.tes.co.ukgetactive Also see “The Issue” on teacher fitness in this week’s Friday magazine