…at least in post-menopausal women on the diet for two years. AJCN has the details:
“It has been hypothesized that hip-fracture rates are higher in developed than developing countries because high-protein (HP) Western diets induce metabolic acidosis and hypercalciuria. Confounders include interactions between dietary protein and calcium, sodium, and potassium.”
In conclusion:
“High dietary protein intake [at least 90 grams/day] during weight loss has no clinically significant effect on bone density….”
Advanced Mediterranean Diet 