For years dieters have been trying to avoid fat, and low-fat products have been promoted as the healthier option. But there is now a great deal of publicity around sugar and its toxic effects on our health, including claims that it is the ‘new tobacco’. The sweet white stuff is being blamed for the obesity epidemic and with it diseases such as diabetes and heart disease. So what is the evidence behind the hype, and what should we as health professionals be advising patients?