Bones strength increases to the age of 35, remains steady for mid-adulthood, then declines by 1-2% per annum but precipitously arpund menopause when bone loss can be 5% per annum for 4-5 years perimenopausally.
Bone strength can also be impacted by activities, lifestyle, genetics, medical conditions more details here
Osteoporosis happens when bones become gradually more fragile. This can progress painlessly, until a bone suddenly breaks. Our bones are made of a thick outer shell, which surrounds a strong mesh network filled with calcium salts, collagen (protein), and other important minerals. When the mesh becomes thin, it can break easily.
In the body, bones are constantly in a state of renewal. Old bone breaks down, and new bone is made. This happens more slowly in old age. In young people, the body makes new bone faster than it breaks down the old bone, so bone mass is increased.
Over time, this process slows down. We reach our peak bone mass level in our early 30s, and from them, bones break down faster than the body is able to create them.
Therefore, the more you produce bone and accumulate bone mass in your younger years, the less likely you are to develop osteoporosis as you age. Think of your body like a bank, saving bone for later in life.