The No. 1 Sunday Times bestseller Why does our body know exactly how much water we need, how much oxygen we need - but when it comes to eating, our systems seem to fail? Why is it that, for several decades, overweight and obesity have become a serious problem around the world, which is becoming more serious with each passing year? Chris van Tulleken points out a single reason that is responsible for this: highly processed foods - they are ubiquitous and cannot be easily avoided even for nutrition-conscious people.