This comprehensive 2019 New England Journal of Medicine review summarizes the impact of intermittent fasting at both a cellular and an organ/body system level. It then outlines how these changes may benefit individuals with a variety of disease states.

While VO2 max might have been considered a gold standard of endurance at some point, we have demonstrated that it is but one of several important variables, and its status as the gold standard is not backed up by data. VO2 max should be regarded as one of many variables involved in fitness, defined as increased work capacity across broad time and modal domains.