Hey, I have a friend that is starting this diet that tells him to do a long fasting of 16h. Basic biochemistry would tell me that most of the weight loss doing this will be due to glycogen and muscle mass loss, simply because gluconeogenesis would be happening quite A LOT if he does a 16h fasting everyday.
The guy that promotes that routine mentions some articles, but they all seem to be about intermittent diets where people eat 20% of their needs in one day (still able to keep blood glucose?) and eat normally on other days. Something like the 5:2 I suppose
Another point to consider would be that people doing (and promoting) that diet are actively training for muscle hypertrophy. Maybe they use other stuff like BCAAs formulas etc.
The only article I could find that would be close to that situation is about Ramadan fasting and performance of football players. Not surprisingly their performance was negatively affected by fasting: journals.tums.ac.ir/abs.asp...
Does something (crazy) like that even deserves a clinical trial?