Good point, DesertLily. My Comprehensive Metabolic report details a high level of calcium (in the blood) of 10.4 mg/dL (normal range is 8.6 - 10.3). Unfortunately my Rapid Response 10-parameter urine reagent strips do not measure calcium. I have not heard of a source that measures calcium in the urine. If not much calcium is excreted by the kidneys, then continuous bone loss would not be so much, as you observe. That would be very good, if true. The urine itself is highly acidic, proving there is not enough calcium in it, at least, to neutralize the ketone bodies there. So maybe the kidneys do not excrete calcium any more than the other precious electrolytes such as potassium. Along with protein sparing, the body knows what it is doing, really a wonderful system. This would be reassuring in case of doing a future fast. Thank you. If you do some more research on calcium excretion, please let me know what you find out.