Ask the doctor: Why do we get shorter as we age?
Q. Why am I shrinking as I'm getting older, and is there anything I can do about it?
A. Our height is determined by the length of the leg bones, the spine, and the skull. While the leg bones and the skull remain pretty much unchanged in length after we reach adulthood, our spinal bones (the vertebrae) tend to shrink. Most of us have 24 vertebrae. They're stacked on top of one another like a roll of dimes, but (unlike the dimes) are tethered tightly to each other by fibers and muscles, so they keep us straight.
As we age, in many of us (men as well as women) the bones start to get thinner. Each of the vertebrae becomes a little shorter. Therefore, so do we. With full-blown osteoporosis, people can lose several inches in height.