What is Osteoporosis?

So what is osteoporosis (in real people language, not just Dr speak)?

Osteoporosis is a commonly misunderstood condition, which is frightening considering how common and debilitating it is. Many people refer to osteoporosis as a lack of calcium, however it is bone density that is lacking, of which calcium makes up a large part. With the loss of bone density, bones aren’t as strong as they should be, leading to an increased risk of a fracture.