This book, edited by Courtenay Young, contains a number of previously published articles about the Science of Body Psychotherapy.
After an Introduction, there is an article by Roz Carroll, an eminent Body Psychotherapist with an active interest in Neuroscience.  Christine Caldwell and Rae Johnson follow with a 'Body Psychotherapy Research 101' article.
Then comes a series of four full-length articles on the Science of Body Psychotherapy by Courtenay Young.  These take the reader on an extended journey, in depth and in detail, and with frank reservations about some of the mistakes made on the way, up to where we are now, and possibly what to look out for in the future.  Another article on the differentiation between Art, Craft and Science in Psychotherapy and Body Psychotherapy follows.
This is followed by a research article from Christa Ventling, showing how efficacy research can be done.   She was awarded the USABP Prize for Outstanding Research in Body Psychotherapy.
Finally, there is a seminal article on The State of the Art in Research by Frank Röhricht, a psychiatrist and academic with a number of research papers to his name, who is also a Body Psychotherapist.
Altogether these give an excellent perspective on the Science of Body Psychotherapy: link here.