12 healthy volunteers took part in a seven-day fast, during which time they were allowed to drink water but could not consume any food . Participants were closely monitored throughout this period, with researchers measuring changes in around 3,000 different blood proteins on a daily basis . As a result, participants lost an average of 5.7 kilograms (12.6 pounds) across the week, and kept this weight off even after they began eating food again .