The Hungry Gene (Hardcover)

"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

The title of this book may lead you, wrongly, to conclude that it's going to be another one of those treatises in which the author blames genetics for everything: criminality, alcoholism and now obesity. Although Shell does look at the research into the genetic basis for our eating habits, she doesn't make the simple equation that bad genes make us fat. On the contrary, she recognizes that our modern environment, where big multi-nationals encourage us to eat heavily processed, high-fat, high-salt, high-sugar foods, plays the greatest part in the obesity epidemic in the Western world. 'Epidemic' isn't an exaggeration. In the US, says Shell, '34 percent of adults are overweight, and an additional 27 percent obese'. Obesity is becoming an even greater risk to health than tobacco, with obese individuals having a much higher chance of contracting serious illnesses such as diabetes and cardiovascular disease. The first half of her book is a page-turning account of the scientific race to discover the genes that underpin appetite. The great finding of this research was that a particular gene, which became known as the ob gene, governs the production of leptin. Leptin is the hormone that tells you when to stop eating; there are a few, very rare cases of people whose bodies don't produce leptin and who are therefore always hungry and, as a result, dangerously obese. But leptin isn't the whole story: give ordinary people extra leptin, and it doesn't, on the whole, reduce appetite. The interaction between leptin and other hormones, and between the environment, is much more complex than that. And so, in the second half of the book, Shell looks at how our modern demands for instant gratification from food and our sedentary lifestyle combine to make us eat, eat and eat long past the point of satiety. Particularly interesting is her description of the Polynesian islands, where the replacement of the traditionally meagre but healthy diet with high-fat imports has created an obesity epidemic even worse than that in the US. Her subsequent account of the impact of a pregnant woman's diet on the developing foetus - most of the factors that will later create an obese individual are present in the womb - will be alarming news to most of us. This is a thoroughly researched, beautifully written book. Shell presents quite difficult ideas, such as the debates among geneticists, very clearly without ever patronising the reader. Yet, surprisingly, her final message is a simple one. How do you say slim? Easy: eat less, and exercise more. (Kirkus UK)