Food plays a different role in our lives, depending on where we live. In the developed world food has become as much about entertainment as about nutrition. On World Food Day, Louise Holden asks if the media is stuffing us with junk about our diets

When the Simpsons sit down for a round of Krusty Burgers they are typical of the modern First World family. Bart and Lisa watch Krusty the Clown on TV, the whole family eats Krusty fast food, Marge serves Chocolate Frosted Frosty Krusty Flakes ("only sugar has more sugar") for breakfast and Homer diets on Krusty brand lo-fat TV dinners.

In the developed world, eating has become all mixed up with pop culture, lifestyle and celebrity. Sometimes it's hard to pick out where nutrition ends and entertainment begins.

We're programmed to eat when we're hungry, but many of us choose to eat when we're bored. We pick an ice cream over an orange for the same reason that we choose a sitcom over a swim. We want instant gratification.

The more television we watch, the more likely we are to eat badly, according to nutritionists. TV programming is full of messages about food. It's not just advertising - in many of the programmes and films we watch, the food's the star. "Product placement" has Pepsi playing a supporting role to Britney Spears in her teen movie vehicle Crossroads, Heinz Tomato Ketchup starring in Seinfeld sketches and Tropicana juice sitting in on breakfast with the Sopranos.

Not only does food star in our entertainment, entertainment stars in our food. Product tie-ins see Lucozade turned to Larazade in a tribute to Tomb Raider, Happy Meals are home to Disney characters and No Problem'Os are Bart's very own brand of cereal. It's no wonder we associate eating with watching TV.

In his book Fast Food Nation, Eric Schlosser describes the close relationship between the entertainment industry and the food industry. "Brad Ball, a former senior vice president of marketing at McDonalds, is now head of marketing for Warner Brothers. Not long after being hired, Ball told the Hollywood Reporter that there was little difference between selling films and selling hamburgers... amid all the marketing deals, giveaways and executive swaps, America's fast food culture has become indistinguishable from the popular culture of its children."

We produce too much food in the developed world, with the result that there's great pressure on manufacturers to sell it. Because we only need a limited amount of food for nutritional purposes every day, food manufacturers need to cook up other reasons for us to eat. Okay, so you're not hungry, but wouldn't it be fun to eat a Teletubbies-shaped chicken nugget?

The basic building blocks of the food we eat - grains and cereals, fruit and vegetables, meat etc - are produced by farmers, but farmers only get a small share - about 20 per cent - of the money that we spend on food. Much of the rest goes to those who take food and turn it into entertainment.

When we buy a soft drink, a fraction of the cost pays for what's in the can - sugar, water, dye and aluminium. The rest of the money goes to pay for the celebrity endorsement, the merchandising rights to put, say, Lara Croft on the can, the salaries of the marketing team and the cost of making the ad that ran during primetime TV. You, the drinker, saw it and thought - "hmmm, I'd like some of that right now".

Marion Nestle, Professor of Nutrition and Food Studies at New York University believes that the number of hours a person spends watching TV relates directly to calories consumed and to obesity.

"The number of TV commercials for foods and beverages has more than doubled in the last 10 years during children's prime viewing hours, and by far the majority of them are for foods of low nutritional value - junk foods," she says.

Most of the food that stars on TV and in film is junk. Once upon a time, Popeye the Sailor used to eat spinach for strength in an undisguised attempt to get children to eat more vegetables. It worked in the 1920s. Sales of spinach increased by a third and it became one of the most popular foods among American youngsters.

But it's hard to imagine broccoli or porridge finding their way into Hollywood movies or Saturday morning kids programmes. They're

not the sexiest foodstuffs in the world. However, maybe if broccoli came in snack-size packs with a pizza-flavoured dip on the side and a chance to win tickets to a backstage party with S-Club, well, maybe we might see Buffy tucking in.