In prosperous countries, large numbers of people – whether they wanted to lose weight or not – became understandably scared of the modern food supply and what it was doing to our bodies: type 2 diabetes, obesity and cardiovascular disease, not to mention a host of other complaints that are influenced by diet, ranging from Alzheimer’s to gout. When mainstream diets start to sicken people, it is unsurprising that many of us should seek other ways of eating to keep ourselves safe from harm. Our collective anxiety around diet was exacerbated by a general impression that mainstream scientific advice on diet – inflated by newspaper headlines – could not be trusted. First these so-called experts tell us to avoid fat, then sugar , and all the while people get less and less healthy. What will these “experts” say next, and why should we believe them?