"Obesity is quickly eclipsing tobacco as the number one threat to public health", according to the American Surgeon General. As Ellen Ruppel Shell reminds us in The Hungry Gene, her timely and well researched exposé, this is not just an American disease: in Britain, youth obesity rates soared by 70 per cent in a single decade. The trend also holds true for Russia and China, Brazil and Australia. As Shell expertly unravels the causes and possible cures for obesity, they turn out, like many addictions, to be much more complex than previously thought. Indeed, a fat-related gene and its product leptin were identified in mice after a prolonged search that"s well described by Shell. But even this is by no means the end of a complicated story that involves interactions between genes, foetal development and environment. On the one hand there are plenty of alarming observations and supporting data about getting fat. For example, using a remote control to change channels on the TV rather than getting up to do so "can add up to as much as an extra pound a year". The book airs other claims and observations: There is "a clear association between the number of hours of television a child watches and the risk of that child becoming obese or overweight". "Childhood obesity in the United States jumped from five per cent in 1964 to 14 percent in 1999." "In Australia, childhood obesity rates tripled between 1985 and 1995, and today one out of every five children there is overweight." On the other hand recent studies have claimed that people who were exposed to famine during their early development in the womb were 80% more likely to be obese as adults. People from many different ethnic groups where obesity has previously been rare can become susceptible within a generation with changing dietary and life styles. And what happens to us whilst we are in our mother"s womb can make a big difference even before we are exposed to the new culture of fast food and slothfulness. Ellen Ruppel Shell is a highly experienced American science journalist who writes for quality journals such as the Atlantic Monthly and Discover. This experience serves her well in putting across such a intricate tale. Proper notes with references and an index make this an invaluable resource as well as a good if worrying read. Right, I"m off for a run. Douglas Palmer