Final answer:
Osteoporosis is a disease involving a significant loss of bone density, primarily affecting older adults and leading to weaker bones and higher fracture risk.
Step-by-step explanation:
A significant loss of bone density is called osteoporosis. This bone disease is prevalent, especially in older adults, and is associated with a decrease in bone density, which results in skeletal weakness and an increased risk of fractures. During our youth, bone formation outweighs bone resorption, but as we age, this process can reverse, leading to thinner bones that are less dense and strong. Factors contributing to this include hormonal changes, illnesses, certain medications, and lifestyle factors such as diet, smoking, alcohol consumption, and lack of exercise. When diagnosing bone thinning, physicians differentiate osteoporosis from conditions such as Paget's disease, which is characterized by an abnormal rebuilding of bone tissue.