I've read that fasting can increase GH levels. Do you know of any studies that directly link fasting to muscle growth? Intuitively I would guess that increased GH in the absence of a calorie surplus might lead to good muscle maintenance but poor muscle growth, particularly in people who already have a decent amount of muscle.
I do not know of studies, other than anecdotes such as this one:
> So, during the FMD I lost approximately 4.2 lbs of body fat, while GAINING nearly a pound of muscle! There was also a nice muscle building “rebound” effect once my fast ended and I began to exercise again.
As someone who regularly fasts for a variety of reasons, I would agree -- it's nearly impossible to gain muscle while fasting anyway, and without working out in any way I can't imagine how that could happen at all.
But most likely the tool is measuring inaccurately.
