But other age-related processes also make us look younger. One of the most important causes is a decrease in bone density, which is thought to be caused by a decline in estrogen and testosterone with age. Vitamin D deficiency and decreased calcium absorption with age can worsen this process, sometimes leading to a bone disease called osteoporosis. As bones become weak and porous, the vertebrae that make up our spine compress under our own weight, leading to fractures. Surprisingly, most of these fractures are painless, which is why we don't notice how our spine shortens over time. This bone loss is common in women after menopause. Posture can also affect body size. For example, if we sit hunched in front of a computer for years, this can lead to degeneration of the spine, making us smaller. A focus on healthy sitting posture, occasional standing stretches, and targeted back exercises are the perfect antidote.