Stretch marks are a huge problem. The problem with stretch marks is
the elastic fibers in skin with stretch marks are damaged, and elastic
fibers are the single hard thing to repair in skin. When you have a wound
that’s healing, our body’s replace the collagen proteins and all the skin
structures that are injured, but the elastic fiber is very difficult to repair.
The trouble with stretch marks is that it’s a defect in those fibers. So
since our body cannot effectively repair those fibers, the stretch marks
do not heal.