Something less beguiling for a horror-story addict than the emergence of obesity would be hard to imagine. Start by reading the 27 August 2011 issue of the Lancet. One article predicts that the obesity rate in the UK will make the tremendous leap from the 25% it is today to 40% by 2030, when its consequences will cost the National Health Service in the UK an extra £2 billion a year. Add to this that more recently researchers reported the body mass index (see illustration of its origin of on page 272), which is used to determine adiposity, underestimates the number of people currently classified as obese by 39%² article published in the Guardian in June this year. Peretti explains that on average people in the UK are 19 kg heavier than they were in the mid-60s. We are not exercising less but we need to exercise more to counteract our change in diet. The main cause for the increase in obesity, which is also associated with an increased risk of many other disorders most notably diabetes type 2, is that we are consuming large quantities of high-fructose corn syrup. This supplement was surreptitiously introduced into our diet by the food industry in the 1970s. Peretti's article recounts a riveting and plausible theory of the political–industrial conspiracy that allowed this disaster to happen.

Next you should read this issue of Medical Writing. You could be forgiven though for asking why, however fascinating and horrific, a medical writing journal should devote an entire issue to obesity and type 2 diabetes. Unlike clinical trials related to cancer and paediatrics featured in recent issues of MEW, diabetes trials do not have sensitive and unique features that affect the preparation of reports on the procedures and results. But, with the incidence of obesity and diabetes set to soar, medical writers are bound to find themselves writing more and more about obesity and diabetes in the future. Accumulating knowledge of the diseases we write about is important. The GATE principles, which define the interaction between medical writers and authors, require that writers have sufficient expertise in the topic or field.⁴

Another reason for focussing on diabetes is personal. I started my career in medical writing as managing editor of Diabetologia and before I pass on the editorship of Medical Writing to Phillip Leventhal, I am keen to highlight obesity and diabetes type 2 as diseases we should all be vitally concerned about.

The pity is that both diseases are largely preventable through diet and physical exercise. An obvious question, then, is why we don't act in our own best interests: eat sensibly and exercise sufficiently to avoid the dire consequences that we are fully aware of. It's a question that Diana Raffelsbauer asks in her article on obesity. Together with Melanie Price she also examines the evolution and causes of obesity: the contribution made by genetic factors, a lack of physical exercise, and ‘toxic food environment’. Did you know that while the price of the flagship healthy food, fruit and vegetables, increased by 118% in the USA between 1985 and 2000, the cost of carbonated soft drinks, which are particularly fattening, only went up by 20% over the same period? Or were you aware that, according to the latest