Munizah Ahmad investigates the claims that fast food manufacturers are corporately responsible for the rising levels of obesity in the western world

In june this year president bush declared a nationwide war on fat, urging Americans to follow his example and make exercise a daily part of their lives. This, at least, is one war that is easy to justify. Sixty-one per cent of Americans are overweight and 20 per cent obese. Furthermore obesity rates among teenagers and children have almost trebled in the last 30 years. Britain is not far behind. Obesity rates here have also trebled in the last two decades, with one in five adults dangerously overweight and one million children clinically obese.

Perhaps the most significant symptom pushing obesity on to the political agenda is the fact that it is costing the NHS around £500 million a year and the economy £2 billion through illness and premature deaths, which currently stand at an annual rate of 31,000. The condition can be linked to heart failure, high blood pressure, strokes, colon cancer and diabetes. Most alarmingly, Type II diabetes, normally restricted to the over 40s, is now emerging in overweight teenagers.

As obesity enters into matters of state, we are inevitably led to ask who is responsible, not only for treating its symptoms, but also for causing its spread. Can the stereotype of the "lazy", "greedy" individual still be targeted as the sole object of blame? A recent report by The Obesity Awareness and Solutions Trust (TOAST) argues that campaigns to encourage healthy eating and regular exercise are not enough. Obesity: a Call for Action asserts that "obesity is not only a health concern but also a social problem." Drawing attention to the psychological triggers, of obesity-related behaviours, it argues that: "As well as looking at the observable behaviour, such as how much is eaten, it is useful to look at what drives food choices; the cognitions and emotions that lie behind."

A recent study by the think tank Demos, Inconvenience Food: the Struggle to Eat Well on a Low Income, provides an in-depth survey and analysis of food poverty in Britain. The study reveals how retail geography, transport and childcare problems as well as the lack of time and money, all contribute to unhealthy diets. One inner London estate observed in the study was 15 minutes from any major supermarket, but had 14 fast-food outlets in close proximity.

The growth of the fast-food industry in its multinational proportions raises the question of the more controversial issue of corporate responsibility. Fears of litigation are rising and indeed began to be realised when a $50 million lawsuit was recently launched against a US food manufacturer over its misleading labelling.

Furthermore it cannot be mere coincidence that the rates of obesity have increased alongside the growing consumption of fast food, which crosses class boundaries but is bound to affect lower-income groups, with their limited choices, the most. As Eric Schlosser, in his bestselling Fast Food Nation, puts it, "the growth of the fast food industry has made an abundance of high-fat, inexpensive meals widely available". The Demos report observes that, among those surveyed: "Eating out tended to involve McDonald's, KFC, the food stands at the market, the chip shop or the kebab shop." This cannot be put down to cost alone. For those who see eating out is a rare treat, the reassurance of predictable, value-for-money food and familiar surroundings is bound to be attractive. Added to the conditioning of these choices is the huge concentration on marketing to children which has led to the banning of advertising during children's television programmes in Holland, Norway, Belgium and Ireland, and all ads aimed at children under 12 in Sweden. Should Britain be taking its lead from Europe or America - where schools earn $750 million a year through sponsorship deals with food companies?

It is easy to argue that people are aware of the health risks when they consume fast food, but can corporations be absolved of their responsibility to make clear the calorific and fat content of their food, which is often obscured by the advertisement of "fresh" and 'wholesome' ingredients? Indeed, as the TOAST report points out, food labelling across the board requires revision. Banners such as "80 per cent fat free" mislead consumers into thinking the product is low in fat. It is not the fat weight of a product, but the percentage of calories from fat which count. Working this percentage out on the basis of the fat weight, normally provided in grams, involves a complex calculation.

Given that obesity is spreading at a huge cost to the health service and the economy while the food manufacturers and fast food empires make huge profits, taxation may go some way towards tackling the problem. In America, there is talk of a tax on fizzy drinks and junk food aimed at children. Here, Demos has proposed a "fat tax" to be levied on "the advertising of fatty, highly processed and fast foods, with the revenues to be spent on promoting fruit and vegetables".

It remains to be seen whether such measures alter our consumption patterns, but they may be a step toward raising awareness of the health risks of obesity and in unravelling the complex causes and webs of responsibility that surround it.