Illustration by Molly Quinn / The Spokesman-Review

I was trying on my suit to make sure I hadn’t outgrown it, when my wife looked me over and noticed — my suit had outgrown me.

Actually, her exact words were, “It looks like you’re wearing a clown suit.”

I had to admit: The suit looked large and baggy.

So I went down to Jos. A. Bank men’s clothing store. The manager, Doug Wester, got out his tape measure and gave me the diagnosis.

I have shrunk. Since I bought that suit seven years ago, I’m an inch shorter and almost a suit size smaller. I ended up buying a new, smaller suit.

As I subsequently learned, I have merely been going through a natural aging process that we might call, “The Incredible Shrinking Baby Boomer.” Gravity was doing its inexorable work of bringing us all back down to earth.

Doctors and anatomists have long known that people tend to lose height as they grow older. This begins at about age 40, although it progresses so gradually that most of us don’t notice it until our 50s and 60s.

That means it’s hitting home, right now, to just about the entire baby boom generation. Wester knows this phenomenon better than most.

“In a lot of cases, I will get gentlemen in here who think they are, for instance, a 44 regular,” he said. “But when I go to fit them, they’re a 44 short. … t’s usually because their body is collapsing.”

Ouch. Isn’t “collapsing” too strong of a word?

To find out, I called Rick Shepard, a family medicine doctor at Group Health’s South Hill Medical Center in Spokane. He explained that your height is largely determined by the length of your spine. Because of normal wear, the spine gradually begins to — not exactly collapse — but to compress, as we age.

Shepard explained that the spine is made up of 24 vertebrae, separated by 23 “pillows or cushions called discs.”

“Over time, that pillow gets a little bit flat, just like the pillow on your bed,” Shepard said.

Also, “you settle a little bit,” Shepard said. By that, he means the actual vertebrae bones, which have interiors “more like Styrofoam,” can become more compact. This compressing and settling may amount to only a fraction of an inch for each set of discs and vertebrae. Yet when you multiply by 23 or 24, you’ve dropped a suit size.

Shepard said that most people lose up to an inch and a half over their lifetimes. Studies suggest that some people lose as much as two or three inches.

The spine is not the only problem. People naturally have spaces between their hip joints and knee joints, filled with cartilage. Over time, that cartilage thins out, like a worn-out “ball joint in a car,” Shepard said.

So, you can lose height not just in the torso, but also in the leg. Which explains why the pant legs of my suit trousers were also a bit too long.

Meanwhile, nonstructural forces are also at work, including “a loss of overall muscle tone” as people age, Shepard said.

“People can begin to slouch and lose a little body posture,” he said. “They don’t stand as straight, from deconditioning and inactivity.”

Osteoporosis — a loss of bone strength — can also cause women to stand less tall. And men are not off the hook, either — “men can get osteoporosis, too,” Shepard said.

People can lose inches not only vertically, but also horizontally, from their shoulder and chest measurements.

“When people age, they slow down and they lose muscle mass through slowing down,” Shepard said.

The result? You might end up shorter and scrawnier.

Of course, many people have the opposite problem, getting fatter as they age. This, as it turns out, might make them even shorter. Extra weight puts extra pressure on the bones and discs, causing them to compress even more.

“It’s the law of gravity,” Shepard said. “It’ll pull you down.”

So there are a few things that a boomer can do to minimize height loss. Keeping to a normal, healthy weight is one. Gravity is merciless enough on its own — don’t give it any extra impetus with an extra 50 pounds.

Staying fit will also keep height loss to a minimum. Regular exercise preserves muscle mass, keeps bones stronger and helps you to maintain good posture.

How regular is regular exercise?

“I tell my patients to shoot for 150 minutes of exercise a week — walking, jogging, biking,” Shepard said. “That’s the equivalent of a 30-minute walk, five days a week. And that’s not unreasonable.”

Shepard uses a simple formula to determine if you are “fit”: “You can walk 3 miles in an hour, and get up the next day and do it again.”

There are also a few other strategies people can use to minimize height loss. Many people take calcium and vitamin D supplements for bone strength, although the benefits are a matter of debate.

Yet even if we follow all of these strategies, a little bit of height shrinkage is inevitable, conceded Shepard. Losing a lot of height in a short time could indicate a serious medical condition, requiring medical attention. But losing an inch or two in the long run? It’s natural, and, for most of us, unavoidable.

Wester, a boomer himself, has seen the phenomenon not just in his customers, but also in himself.

“I just went to the doctor the other day, and I have always been 5-6,” he said. “Well, I’m not 5-6 anymore.”

I could find no studies on the psychological effect of height-loss. Yet from my experience, I can guarantee that they exist. After 40 years of being a certain height, I suddenly discovered that my driver’s license — along with my entire self-image — is wrong.

This can seem particularly tough on men like Wester and myself, who grew up fighting, tooth and claw, for all of the inches we could get. And now we find ourselves losing yardage — literally — in our 60s. Is this fair?

Our only consolation is that all of our fellow baby boomers — even the tall ones — are shrinking right along with us. Meanwhile, everyone under 40 will inevitably discover what many boomers already know: The top shelf has, for some mysterious reason, become an inch higher.