In other cases (such as the rise of franchising and the spread of obesity), fast food has played a central role. In some cases (such as the malling and sprawling of the west), the fast food industry has been a catalyst and a symptom of larger economic trends. Fast food and its consequences have become inescapable, regardless of whether you eat it twice a day or have never taken a single bite. During a relatively brief period of time, the fast food industry has helped transform not only our diet, but also the landscape, economy, workforce and popular culture. The early Roman Republic was fed by its citizen-farmers the Roman Empire, by its slaves. What people eat (or don't eat) has always been determined by a complex interplay of social, economic and technological forces. They spend more on fast food than on movies, books, magazines, newspapers, videos and recorded music - combined.

Americans now spend more money on fast food - $110bn last year - than they do on higher education. Fast food is now served at restaurants, stadiums, airports, zoos, schools and universities, on cruise ships, trains and aeroplanes, at supermarkets, petrol stations and even in hospital cafeterias. Over the past three decades, an industry that began with a handful of hot dog and hamburger stands in southern California has spread to almost every corner of the globe. It has become a social custom as American as a small, rectangular, hand-held, frozen and reheated apple pie. The whole experience of buying fast food has become so routine, so thoroughly unexceptional and mundane, that it is now taken for granted, like brushing your teeth or stopping for a red light. Watch teenagers in uniforms pushing various buttons, and moments later take hold of a plastic tray full of food wrapped in coloured paper and cardboard. Pull open the glass door, feel the rush of cool air, walk in, get in line, study the backlit colour photographs above the counter, place your order, hand over a few dollars.

The fast food nation