In the world of office work, we’re seeing a dichotomy. Or is that just a glare off a car in the parking lot? No, I’m pretty sure it’s a dichotomy.

According to a recent report in PLoS One – it’s the journal of the Public Library of Science, not a government program to improve spelling and capitalization – one reason Americans are getting so fat is that our jobs are too easy.

Not easy in the sense of being pleasant or rewarding or anything like that, but in the sense that we just sit in front of our computers all day like lumps of suet.

In the good old days, most jobs involved a fair amount of physical activity. Cheerful longshoremen sprinted toward limousines to collect payoffs from the Mafia. Fun-loving construction workers offered comments to passing women and then scrambled to avoid the slaps. Merry carpenters competed to see who could carry the most shingles to the roof before remembering that they were supposed to be installing kitchen cabinets.

Then Iowa State University invented the electronic computer, immediately traded the rights for some magic beans, and the world of work changed forever.

Automation replaced factory workers, GPS devices replaced getting out of your car and walking into a gas station for directions, and email replaced carrying a stack of papers down the hall to your boss.

Also, Carl Yastrzemski replaced Ted Williams in left field, but that was pretty much just Ted’s problem.

According to The New York Times’ report about the report, “Jobs requiring moderate physical activity, which accounted for 50 percent of the labor market in 1960, have plummeted to just 20 percent.”

And that’s part of the reason we’ve transformed from a nation of lean, solid citizens constantly doing the Twist to a bunch of lardos who keep thinking: “Why does this TV remote have to be so heavy?”

Now for the other half of the dichotomy. (Remember that concept, clear back at the beginning? These columns really should come with some kind of index.) Today’s office workers seem to be much more interested in physical fitness and sensible diet than ever before.

The other day, a young woman at a big company was describing the strenuous workout that’s part of her daily routine, and telling me that her employer provides personal trainers and dietitians. I was just glad that she let me use the elevator, and that she didn’t challenge me to a scaled-down racquetball game on the way up.

Or sometimes I’ll have lunch with a successful business person, and that person, no matter what gender, will choose a salad. I feel bad as I order a pizza topped with Graziano Bros. sausage, but the feeling actually isn’t all that hard to shake.

“The shift translates to an average decline of about 120 to 140 calories a day in physical activity,” said the Times, “closely matching the nation’s steady weight gain over the past five decades.”

We should be able to counteract that rather easily. Let’s go to the calorie-burner calculator on healthstatus.com.

A mere 10 minutes on an elliptical trainer would burn 155 calories in my case. Walking for 25 minutes at 3 miles per hour would use up 148 calories. Or, if your workspace is big enough and people usually pay attention when you yell “Watch out!” just 30 minutes of archery burns exactly 140 calories.

Doesn’t that sound better than returning to the way America used to live, with you bolting chrome bumpers onto Oldsmobiles all day long?

We had better get at it and lose enough weight to make the researchers lose interest, or the pressure could become intense. The Times story mentions “treadmill-style desks” and “encouraging face-to-face communication.”

Let’s not get carried away.

Jim Pollock is the managing editor of the Des Moines Business Record. He can be reached by email at jimpollock@bpcdm.com