Using a seemingly contradictory statement that if interpreted properly makes sense is often employed in poems and quotations to shed light on a fundamental truth. It’s called paradox.

Want to make a bunch of seventh graders’ heads spin? Ask them to explain one.

Like Sir George Pickering’s “Not everything that counts can be counted, and not everything that can be counted counts.”

Year after year I’ve dumbstruck class after class with that one, but the silence is temporary. Invariably, some insightful soul sees beyond the contradiction and says something similar to this.

“What that Sir George guy means is that good qualities - like being conscientious, courageous, curious, and creative - can’t really be counted. And that having them is more important than having things that can be counted like designer clothes or expensive cars.”

An explanation like that usually spurs on a discussion that leads to a greater understanding of Pickering’s paradox.

To gain a greater understanding of why you should count calories if you want or need to regulate your weight, here’s my attempt to make you feel like a seventh grader hearing Sir George’s words for the first time.

While impossible to do accurately, counting calories is absolutely necessary.

I began a food log in January of 1985 and have recorded everything I’ve eaten (except for nine days I spent in hospitals after bicycle crashes) since then. Early on, however, I knew I was making some significant mistakes weighing and measuring my foods.

Based on how active I was, my daily caloric totals were too low - generally by 20 to 25 percent. The inaccuracy bothered me until late March when I looked at myself in a full-length mirror.

My abs were clearly more defined than before I began my food log. Same for my quads, the muscles most responsible for pedaling a bicycle.

So I stepped on the scale, something I didn’t do during the winter back then. I was two pounds heavier.

More muscle. Less fat. Hey, this counting calories stuff was working.

So what if the numbers at the end of each day were so low that I should look like a rawboned boy? Now that a target number has been established, my miscounting wouldn’t create a problem as long it remained consistent.

That’s true for you, too. An accurate calorie count is not the be all and the end all.

Maintaining a healthy weight while you retain as much muscle mass as possible as you age is.

To further illustrate why accurately calculating calories is impossible, consider the change in the label of the brand of green beans I wrote about in a recent column. According to the updated label, I now get 25 percent fewer calories in each can - even though the size and the ingredients haven’t changed.

But I still use the old number rather than the new one in my calculations to make sense of a system inherent with inaccuracies. Remember, all the acceptable ways food processors calculate calories are already estimates - and the FDA allows a 20-percent margin of error on top of that.

A more dramatic change occurred with Fiber One cereal.

I know because since the mid-1980s, I’ve eaten about three boxes of it a week. And since the mid-1980s, General Mills listed a half cup as a serving - until the FDA mandated that serving sizes must be based on the amounts of food and drink that people typically consume, not on how much they should consume.

As a result, the serving size increased to two-thirds of a cup, and although the ingredients remain the same, calorie count also changed from 120 to 135 calories per cup.

Eat three boxes a week as I do, and that’s a difference of 630 calories. How is that possible if none of the ingredients changed?

It isn’t.

I was consuming those 630 calories well before the label told me so. Because of a similar serving-size change where all ingredients remain the same, I was also consuming 120 more calories of shirataki noodles per week - but 120 fewer calories of fat-free Greek yogurt than I thought.

A quick count brings to mind seven other such changes in the packaged foods I typically purchase. Since I’m only shopping for one person and purchasing mostly fresh vegetables, my guess is that your number would be far higher.

Despite this, I still advise you to count - or should I say miscount? - your calories each day. The increased awareness from weighing and measuring and logging outweighs the inaccuracies inherent in it.

And that’s not true just for a nutrition nerd like me.

A 2010 study published in the Journal of Consumer Affairs of 3,700 people who were trying to control their weight and between the ages of 37 and 50, found that those who did no exercise but read nutrition labels (even without the weighing, measuring, and logging I suggest) were more likely to lose weight than those who exercised but did not read labels.