I took a look for studies and could only find a few.
I also checked the Mayo clinic site, which I generally find a decent site, and found a review by a physician who seems to have good credentials. Here is the piece:
I guess I am a ‘I would rather eat a sensible balanced meal’ sort of person over a ‘diet of the week’ person. I know some people are really motivated by trying new things.
My worries would be:
People should be screened carefully for things like osteoporosis, or anything else where shaking would be a problem.
People would try to use it as an alternative to rather than an addition to active exercise and thus would limit their benefits.
and to me most importantly
Buy buying into the idea that gains can be gotten passively a person looses the opportunity to work their ‘muscles’ of motivation and self efficacy. I believe that the process of coming to the mat is as important as what we do when we get there, and the skill of coming back every day strengthens our ability to come back to other tasks that may be difficult.