Intermittent fasting has been the most powerful thing for weight and health, according to Gin Stephens. It's not a diet, but about when you eat. Time-restricted eating is the most common form, with a 10-hour eating window. The world's biggest intermittent fasting study is being launched by Zoe, aiming for 50,000 participants. It's a real-life study on a scale 1,000 times bigger than before, looking at real-life results and how it might work as public policy. Intermittent fasting is a way to reduce calorie intake without counting calories. It also affects the body's use of fuels and the role of gut microbes. Early animal studies with rats unintentionally showed the benefits of time-restricted eating. The study is open to everyone and doesn't cost anything.