Burn, baby, burn: the new science of metabolism

Losing weight may be tough, but keeping it off, research tells us, is tougher - just not for the reasons you might think

As the director of the Energy Metabolism Laboratory at Tufts University, Massachusetts, Susan Roberts has spent much of the past two decades studying ways to fight the obesity epidemic that continues to plague much of the western world.

But time and again, Roberts and other obesity experts around the globe have found themselves faced with a recurring problem. While getting overweight individuals to commit to shedding pounds is often relatively straightforward in the short term, preventing them from regaining the lost weight is much more challenging.