I’m left bewildered: there are more questions than answers in most scientific pursuits, but I want to stress the point here that these aren’t rhetorical questions.
But in the short-term (at least up to a week for most people), I believe you can maintain muscle mass while fasting, particularly if you’re resistance training.
All of this is very interesting, but what I find much more interesting in this study is that the placebo group did not lose any substantive LBM, while losing about the same amount of fat (10 lb) as the testosterone group, despite the severe CR/energy-deficit.
The purpose of the study was to find out if fasting could protect the intestines from high-dose radiation, which could allow for higher doses of radiation treatment in killing pancreatic tumor cells.
“The great majority of how we understand disease, and attempt to cure it,” writes Engber, “derives from a couple of rodents.” About 4/5ths of all animal studies reported in biomedical research papers from 1950-2010 were done in rodents (59% in mice, 18% in rats).