I found this good study today https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4338319/
In conclusion, we demonstrated that ghrelin regulates bone remodeling by affecting osteoblasts. We also clarified that ghrelin does not regulate bone remodeling via the central nervous system. We unambiguously demonstrated that ghrelin plays a physiological role in bone remodeling, consistent with the observation that ghrelin possesses many physiological functions in addition to the regulation of energy homeostasis and appetite, and is implicated in the pathogenesis of ischemic heart disease [41] and various cancers [42]. Given that there are several ongoing clinical studies on the effect of ghrelin on various diseases, such as cancer-induced cachexia and anorexia nervosa [43], our current observation provides evidence that ghrelin can also be used as a potential therapeutic for osteoporosis.
So can we say that fasting can be used as a potential therapeutic for osteoporosis?