You eat. A lot. At breakfast you're planning lunch. At lunch you're planning dinner. At dinner you're planning a midnight snack. You're constantly aware of food around you, and your hunt to satisfy what seems to be an insatiable desire to be sated is a defining characteristic. You're fat, of course, and why shouldn't you be, considering how much of a pig you are? The books tell you it's a simple equation--calories burned versus calories consumed. But there's got to be more. And there is.

Ellen Ruppel Shell, a science writer and contributing editor with Atlantic Monthly, has put forth the most interesting report on the eating landscape since Fast Food Nation. It's called The Hungry Gene: The Science of Fat and the Future of Thin, and it examines all the complexities that have shaped the obesity epidemic around the globe.

Shell takes us inside the backstabbing world of genetic research, where a race to find the obesity gene, called ob, has multimillion dollar stakes. With admirable clarity, She is able to distill highly scientific tales into layperson's language, and we're able to see that the discovery of the ob gene's protein, leptin, is a huge leap forward in understanding how DNA abnormalities hardwire some people to have faulty satiety sensors.

Shell also takes us to the South Pacific island of Kosrae, a Micronesian state where nearly 85 percent of adults age 45 to 64 are obese, and traces how its history of frequent decimating famines created a survivor population with Darwinian "thrifty genes" that hold on to fat. These genes, crossed with the damaging influence of Western food (Spam is popular here) that has all but replaced the natural diet of fish and fruit, has caused a health disaster.

On the other end of the spectrum, Shell analyzes what some call the "French paradox"--rich food, skinny population--nixing the idea that sons and daughters of Brillat-Savarin have a fat pass. She notes that this is an eating culture based on mindfulness, etiquette and moderation: "In France an adult loping along with a dripping ice cream cone is considered a figure of fun." As far as the French genes go, even though there is famine and plague in that nation's history, this country with a bounty of natural resources has had "fewer decisive 'bottleneck' events than, for example, the tempest tossed islands of the South Pacific."

The factors leading to obesity are exceedingly complex, and, while science has had some eureka moments, the cures are still elusive. While Shell is clear that fatness "represents a triumph of instinct over reason, and as such it embarrasses us," she is equally emphatic that biology needn't be destiny. The one thing we can control is how much we exercise and what kinds of foods we stuff down our gullets. "We can and should resist," she writes. "We can begin by expressing indignation at the conditions that brought us here."

Sound like a resolution? Happy New Year.