Peter Attia defines fasting as prolonged fasts (more than a day) and time-restricted eating (TRE) as periods of not eating within a 24-hour cycle.

“I typically don't use the term intermittent fasting I use the term fasting and I use the term time-restricted feeding or Tim restricted eating to describe what I think most people think of when they say intermittent fasting but as a general rule intermittent fasting or Tim restricted feeding or time restricted eating refers to periods of not eating during the course of a day so when you hear people say I do you know 16 or 186 intermittent fasting of course what they mean is I'll go 16 hours a day without eating 8 hours a day of eating or 18 hours without and 6 hours with fasting is a term I kind of reserve for prolonged fasts anything that's more than a day”