In February, Robert F. Kennedy Jr., the US secretary of health, made a characteristically bold claim. A doctor at Harvard University, he proclaimed, “has cured schizophrenia using keto diets”. If you happened to be passing Harvard University that day, you might have heard the sound of that doctor’s palm hitting his forehead. “For the record, I have never ever once used the word ‘cure’ in any of my work,” says Christopher Palmer, a psychiatrist at Harvard Medical School. “Nonetheless, I have used the word ‘remission’…” The idea that a diet best known as a fat-busting fad could treat serious mental illness might sound like the latest offering from the wild west of online wellness: something destined to be filed alongside raw water and coffee enemas in the annals of terrible suggestions. But there are a number of reasons why the idea of using the diet for conditions affecting the brain deserves closer inspection. For one thing, over 100 years’ worth of research has shown that ketogenic diets have real, measurable effects on the body in general, as well as on the organ between your ears. For another, many of these changes – some at the cellular level, others throughout the whole body – are known treatment targets in mental illness. With evidence from small trials and case studies indicating that ketogenic diets can dramatically …