How does immobilization cause osteoporosis?

Osteoprosis: If I want to put it in a simple way, it affects the bone remodeling with increasing bone absorption and decrease bone production.

Immobilization: Hi. Both weight-bearing and muscle use are good for bone health. You're not weigh-bearing OR using muscles if you're immobilized. Skeletal mass and strength suffer. It appears that the cells that eat away bone (osteoclasts) are relatively more active than the cells that fill the eaten-out bone back in (osteoblasts), so there's a net loss of bone mass and bone architecture & urinary loss of calcium