Gray hair can be colored. Flab can be fashionably dressed. Crow's feet can be ironed out. But just when it seems there's no symptom of aging that can't be tamed, it can come creeping up on you. Or creeping down.
The Shrink. That gradual erosion of stature that hints (and sometimes shouts) that you are past your peak and sliding swiftly over the hill.
In the beginning, of course, it's easy to ignore and rationalize The Shrink. You're not growing shorter, your kids and grandkids are just getting taller.
Some shrinking with age probably is inevitable, most experts agree -- but not as much as you may be blaming on birthdays alone. When height loss is so great that others start to notice, many experts now say, it could indicate an underlying problem. For example, a typical patient treated at Johns Hopkins University's Gerontology Research Center "might be a woman in her late sixties, who has lost an average of three inches" due to a variety of reasons, including menopause, having her ovaries removed or having suffered bone injuries.
Men experience less shrinkage than women, according to Dr. Michele Bellatoni, an assistant professor of geriatric medicine at Johns Hopkins University, but some men are more prone than others.
"Some men who smoke, use steroids for medical conditions, or who may have had their prostate removed may lose more bone strength," says Dr. Bellatoni.
While the risk of osteoporosis is partly determined by factors out of your control, many behaviors that lead to height loss -- smoking, sedentary lifestyle, poor body mechanics or posture -- can easily be altered.
"It is normal not to shrink," says K. Michael Davies, a researcher at the Osteoporosis Research Center at Creighton University, Omaha. It's possible to reach the golden years, he says, at the same or about the same height as you were in your young adulthood.
To better understand shrinking in the later years, it helps to know there are really two types: senior shrink, and the day-in, day-out shrink that happens long before you're eligible for movie discounts.
From dawn to dusk, it's not unusual to lose nearly a half-inch in height, says Dr. Charles Prickett, an orthopedic surgeon and University of Southern California associate clinical professor of orthopedics who also directs a spine clinic at Orthopaedic Hospital, Los Angeles. "You're at your tallest when you wake up," Dr. Prickett explains. "By late afternoon and evening, you have settled."
The fluctuation is due to normal functioning of the intervertebral disks -- the fluid-filled cushions between the 33 vertebrae, the bones that make up the spine.
"People think of bone as static, but it's dynamic," says Dr. Mauro Giordani, a Pasadena orthopedic surgeon.
With daily activity, fluid diffuses from the disks into the vertebral bodies, the building blocks of the spine, Dr. Giordani and Dr. Prickett explain. With less fluid, the disks provide less cushion. And you become shorter. When you lie down, fluid moves back into the disks, and you're back at full height by morning.
Over the years, the amount of fluid decreases. Cushioning decreases. You get the rest of the picture. Stay in good health, and this settling effect will have a negligible effect on your height, many experts concur.
But other factors -- some under our control, others not -- can take their toll on height. "Truck drivers, for instance, are bouncing up and down all day," Dr. Prickett says. That's very tough on the spine.
Those who sit for long periods also put more stress and strain on the spine and its cushions. Diabetics are especially prone to loss of disk resilience. Smokers do their bones no favors. Smoking reduces circulation within the small blood vessels that deliver oxygen-rich blood to the bones, Dr. Giordani explains. The diminished blood supply, in turn, hinders the ongoing process of bone restoration and healing. Calcium stores decline.
Poor posture can also exaggerate The Shrink, although, with practice, it can be corrected.
"Older people are known to slump," says Dr. Loren Lipson, chief of the division of geriatric medicine at USC. "This slump on average can take off 1.5 inches."
By far, though, the biggest height robber with age is osteoporosis, a disease marked by low bone mass and deterioration of the bone tissue. This in turn leads to fractures of the hip, wrist and spine, deformities such as stooped posture or a dowager's hump -- and a decrease in height.
While half of all women in the United States will be afflicted with osteoporosis, according to the National Osteoporosis Foundation, men aren't immune. By age 75, a third of men have the disorder, too, according to foundation estimates.
Height loss due to osteoporosis often becomes noticeable around age 50 in women and 60 or 65 in men, says Dr. Charles Sharp, an endocrinologist specializing in metabolic bone disorders and a USC clinical associate professor of medicine.
Certain people are at much higher risk of getting osteoporosis. Among risk factors: menopause before age 45, low calcium intake, cigarette smoking, excessive drinking and inactivity. Whites and Asians are at higher risk than other ethnic groups; thin people have higher risk than heavier people.
How much height can osteoporosis take?
"I have seen women lose two or three inches over 15 or 20 years," Sharp says. "I've even seen women who have lost six inches."
While you can't control some risk factors for height loss, there are some ways to reduce the odds. Among the experts' suggestions:
* Don't smoke.
* Do engage regularly in weight-bearing exercise, but don't become a fanatic, says Dr. Prickett, who contends overdoing is as bad as doing nothing. Moderate walking, swimming and stationary cycling are the best for bone health, he says.
In a recent study conducted at Texas A&M; University, post-menopausal women who exercised on stationary bikes three times for 30 minutes a week built bone mass by 3.5 percent in their lumbar spines, found researcher Susan Bloomfield, while sedentary women lost 2.4 percent of their bone mass during the same eight-month study. Water aerobics and resistance training with light weights are also good choices, says Dr. Sharp.
* Take vitamins and minerals. Pay attention to calcium, copper, zinc and manganese -- all important for bone maintenance. Teen-agers and young adults should build as much bone mass as possible before age 30, when it peaks.
* Consider a bone-density test. Such a test can help those at high risk for osteoporosis predict the chances of fracture and differentiate spinal osteoporosis from other spine problems.
* Discuss with your doctor whether you're a good candidate for estrogen replacement therapy. Women experiencing menopause, when bone mass decreases, can consider this option to help maintain bone.
If height loss at any age seems sudden or extreme, it could signal an abnormality such as disk disease leading to scoliosis (an abnormal spine curvature) or compression fractures, Dr. Prickett says. If you have lost a half-inch or more before your mid-40s, it bears checking with a physician, Dr. Sharp suggests.