In mid-February, some of the world’s 1.4 billion Catholics started fasting or abstaining for Lent, the 6 weeks before Easter. From next month, Muslims will be obliged to fast from dawn until dusk each day during Ramadan, the 4 weeks leading up to Eid-al-Fitr. At first glance, it looks like tough-going: after all, getting enough food is key to staying healthy. But for people needing or wanting to diet, it turns out that copying a fast is the way to go, according to results of a University of Southern California (USC) trial published in the journal Nature Communications in February. “Cycles of a…