Short Order: The Reason Why We Shrink in Height As We Get Older

Humans tend to stop growing in height between the ages of 16 and 21. And from there, it’s more or less expected we’ll remain at that stature until we die. But that’s not quite how it works. Many people actually begin shrinking as they age, losing up to 3 inches in height by the time they’re in their 70s.

Why can’t our bodies seem to remain vertically stable? Why do we get smaller as we get older?

According to Live Science, diminished height is a multifactorial process. But the main culprit is a loss of bone mass. Between the ages of 40 and 50, our bodies start to lose more bone than they can make. The loss is not just about decreased bone density: It also weakens what’s known as the bone matrix, or the collagen infrastructure that connects bone tissue. With less structural support, bone can suffer microfractures that gradually decrease bone mass. The resulting damage can lead to osteoporosis and a loss in height when vertebrae are involved: The compression can shave millimeters, and even inches, off one’s height.

A 1999 study published in the American Journal of Epidemiology examined 2084 men and women who had their height measured on a regular basis over 35 years as part of their enrollment in an aging research project. Between the ages of 30 and 70, men lost 1.2 inches and women 2 inches. By 80, the loss had progressed to 2 inches for men and 3 inches for women. If you spend adulthood over 6 feet tall, it’s possible you might be present at your funeral at 5 feet, 10 inches. (Good thing you’ll be lying down.)

But bone loss isn’t the only cause. Poor posture can lead to curvature of the spine, which results in being hunched over and a loss of height; normal degradation of discs between vertebrae can also contribute to shrinkage.

For women, menopause can also usher in a loss of height: Estrogen, which diminishes with age, helps protect bones.

Can you avoid it? Not necessarily, but you can do things to mitigate the damage. Bone loss is correlated with loss of muscle mass. If you maintain muscle through exercise, you might stave off bone atrophy and have an easier time standing upright thanks to abdominal muscle, which supports and improves posture.

While some loss of height is normal, losing it earlier or faster is not. Anyone noticing a radical decrease in height should be examined by a medical professional.

If you’re determined to offset shrinkage, consider a sabbatical in space. Astronauts often experience an increase in height due to the lack of gravity on the vertebrae, leading to a gain of up to 3 percent. Once they return to Earth, however, the gains typically vanish.

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