Junk food companies in America are to warn consumers that eating too many of their products could make them fat. 

   In a move designed to protect companies such as McDonald's and Coca-Cola from the kind of lawsuits brought against the tobacco industry, an industry-funded organisation will begin its advertising campaign -codenamed Activate -in a fortnight. 

   "It is designed to help kids between the ages of 9 and 12, and their parents, to improve their eating and activity," Michael Mudd, a senior vice-president at Kraft Foods, one of America's biggest makers of snack food, said. 

   The campaign, which is starting with a $ 2.4 million (Pounds 1.6 million) online marketing project and then television and press advertising, is expected to cause uproar in a country whose citizens spent $ 110 billion last year on junk food. A quarter of the adult population visits a fast food restaurant such as McDonald's or Burger King every day. Lawyers and food industry experts say that the project, which is being backed by the International Food Information Council foundation, could lead to packaged foods such as chocolate biscuits and crisps having cigarette-style health warnings. 

   Food industry executives, however, are playing down such speculation. 

   Industry backers include McDonald's, Coca-Cola, Burger King, Pepsi, Heinz, Unilever and Monsanto. 

   Health warnings about the dangers of overeating could eventually appear on British food labels. The Food Standards Agency was unaware last night of the developments in the US, but Sir John Krebs, the chairman, is anxious for consumers to have as much nutrition information as possible. 

   The agency view at present is that food labels are small and consumers are often confused by the plethora of food facts on packaging, though officials are keen to give the best information possible. 

   American critics of the industry say that it has been panicked into the move by a report last December by David Satcher, the Surgeon General. In unusually blunt language, he said that obesity-related health problems were costing America $ 117 billion a year. Smoking-related diseases cost just $ 23 billion more. 

   "Overweight and obesity may soon cause as much preventable disease and death as cigarette smoking," the report said, adding that 300,000 deaths a year were caused by the problem, compared with 400,000 from smoking. 

   A few weeks after Mr Satcher's report, the Internal Revenue Service, the US equivalent of the Inland Revenue, classified obesity as a disease, allowing overweight Americans to deduct the cost of treatment from their taxes. 

   In this climate, junk food companies are becoming increasingly agitated by talk of tobacco-style lawsuits against them. 

   John Banzhaf, a law professor at George Washington University who helped to pioneer multibillion dollar lawsuits against cigarette manufacturers, is among those to talk about suing food companies for obesity-related health costs. "There's a real change in the public attitude towards obesity, similar to that change that took place with tobacco," he said. 

   He said that four recent lawsuits against food companies, including McDonald's and Pizza Hut, were just the start of a trend. Professor Banzhaf said that tobacco lawsuits started out small, but soon grew as public outrage intensified. 

   He said that if the Government failed to act the courts would. "You watch television any night and see commercials for cheeseburgers, triple cheeseburgers and not once have I seen one that says, 'Warning: twice your daily recommended amount of fat'." 

    But the industry says the Activate programme is not related to fear of obesity lawsuits. "We began researching the increasing incidence of obesity when it started to happen three or four years ago," Sue Borra, one of the information council's officials responsible for the campaign, said. 

    Ms Borra said that obesity was related to much more than just junk food. "It's about the use of automobile, the television, the internet, the lack of time to cook at home -it's a pretty complex issue." 

   Food companies are not only concerned about lawsuits. Campaigners also argue that junk food such as Big Macs should be taxed like cigarettes. The billions of dollars raised from the "fat tax" -also known as "heavy duty" -should be used to fund anti-obesity education projects. In the states of California and Vermont, plans for fat taxes have been proposed by senators, but were rejected after lobbying by the food industry. 

    Marion Nestle, of the Department of Nutrition and Food Studies at New York University, is one of many academics who believe that a fat tax is now the only option available. 

   "We've tried willpower and we know it doesn't work," she said. "And willpower doesn't work because there's $ 30 billion worth of food marketing, much of which is designed to evade common sense." 

    According to the Centre for Science in the Public Interest, a political think tank in Washington, a one-cent tax on every 12oz soft drink would generate about $ 1.5 billion in revenues every year. A one-cent tax on every pound of sweets, crisps and other snacks would raise about $ 314 million. 

 COMPANIES FUNDING THE ACTIVATE PROGRAMME 

* Unilever Bestfoods: Bird's Eye, Ragu, Findus, Hellmann's mayonnaise, Knorr soup, Magnum ice cream, Flora margarine, Lipton tea. 
* Procter & Gamble: Pringles, Sunny Delight 
* Sara Lee: Sara Lee chocolate cake, Douwe Egberts coffee 
* Heinz: Linda McCartney Meals, Weight Watchers, StarKist, 
* Hershey Foods: Cadbury Creme Eggs, Kit-Kat, Twizzlers. 
* Nestle: After Eight mints, Crosse & Blackwell, PowerBar, Quality Street, 
* Kraft: Toblerone, Terry's Chocolate Orange, Ritz, Philadelphia, Diarylea, 
* Bird's Custard 
* Burger King * McDonald's 
* Pepsi (includes Mountain Dew) 
* Coca-Cola (includes Fanta, Sprite) 
* Kelloggs (breakfast cereals, Pop Tarts) 
* Ocean Spray Cranberries 
 

 In a country where the Government is often accused of caving in to the interests of large corporations, legal activists have coined a simple motto: "If you can't regulate, litigate". 

 In the US, lawsuits, or the threat of them, now have almost as much influence as law-makers over the way large companies treat their customers. 

 Almost every industry from car-makers to chemical manufacturers has been forced to respond to the compensation culture, but the most deeply affected are the tobacco companies, whose very existence has been threatened. The junk food industry is the latest to fall prey, but the payouts could dwarf even the astronomical settlements made by cigarette-makers. Obesity triggers Pounds 80 billion of medical bills each year and causes 300,000 premature deaths. 

 The industry's action yesterday shows it is not taking any risks. 

 When the lawyer John Banzhaf pioneered the notion of suing tobacco companies in the mid-1960s for the health problems they caused, everyone thought he was crazy. Thirty years later, the big five tobacco companies have been forced to settle a Pounds 130 billion claim made by US state governments to pay for the health costs of treating their citizens made ill by smoking. 

 The argument was that the tobacco companies made inflated profits by failing to make public their knowledge of the harm done by their products. If people knew how damaging smoking was, it would be their responsibility (the so-called voluntary assumption of risk). But in endless lawsuits, lawyers argued successfully that they did not know, and so the responsibility fell with those who made and sold the cigarettes. 

 The tobacco companies argued persistently that cigarettes caused no harm, but were eventually forced to concede defeat under a barrage of scientific evidence and leaks from employees disgusted at the dishonesty of their employers. 

 Eventually Philip Morris broke ranks and admitted that tobacco caused harm, but it was not rewarded for its honesty. Last year it had to pay Pounds 60 million to a Californian cancer patient, and even that enormous amount was reduced from the Pounds 2 billion it was originally ordered to pay. 

 Tobacco is now an industry in retreat, unable to advertise its products on TV, its customers unable to use them on aeroplanes and in many bars, and its share price in the doldrums. 

 Flushed with success, legal activists have started targeting food companies, with some victories in the initial skirmishes. 

 Hindus from Seattle and other cities sued McDonald's for claiming that its chips were cooked in 100 per cent vegetable oil, a statement that was true but failed to mention that they were pre-fried in beef fat. The Hindus claimed that it was an offence to their religion and constituted an "intentional tort". 

 McDonald's admitted it was in the wrong, and was forced to make a grovelling apology and a Pounds 6 million settlement. 

 Pizza Hut has been sued on similar grounds, with litigants claiming that their Veggie Delight pizza contains beef products. The makers of some corn and rice puffs called Pirate's Booty are being sued after tests conducted by Good Housekeeping magazine showed they contained 340 per cent more fat than was stated on the packaging. 

 The junk food industry feels it can no longer ignore the threats from its customers.