Read the Wired
Cronise got the idea back in 2008 while watching a TV program about Michael Phelps. The coverage claimed that, while training, the Olympic swimmer ate 12,000 calories a day. At the time, Cronise was on a diet of 12,000 calories per week. (He was carrying 209 pounds on his 5’9″ frame and wanted to get back down to 180.) Something didn’t add up. Even if Phelps had an exceptionally high metabolism and swam three hours a day, he still should have turned into a blob. Then it hit Cronise: Phelps was spending hours every day in water, which was sucking heat from his body. He was burning extra calories just to maintain his core temperature of 98.6.