A large brown bear is shown to symbolize a "dad bod."
If your cute and cuddly physique is an improvement from a year ago, then you’re on the right track. (For Spectrum Health Beat)

For the sake of illustration, let’s pretend a man’s picture of good health falls someplace on a horizontal line.

On one end, you’ve got the late John Candy; on the other, you’ve got the very much alive Dwayne “The Rock” Johnson.

For the average guy, there’s probably going to be a comfortable middle somewhere along that vast spectrum.

You may, for instance, be content with a body type more akin to the one Leonardo DiCaprio had on display one recent summer when he was photographed vacationing someplace warm and expensive.

Always the picture of prepossessing boyishness, the Oscar winner looked, in this instance, more like a cuddly dad from Des Moines and less like a toned Titan of Tinseltown.

And if the Internet’s collective brilliance has the last word on the matter, that’s perfectly OK.

Sometime in recent years, folks began dubbing this look the “dad bod.”

Countless celebrities have been photographed unabashedly displaying their dad bods—an online search bears infinite entertaining results—and millions of fathers have been consigned to this body type ever since the developed world became less agrarian and more sedentary.

One college newspaper writer gained some notoriety for suggesting that the dad bod maintains, perhaps, a certain kind of appeal.

It’s a fleshy-but-not-obese physique that suggests, “Let’s skip the gym this weekend, because I’m down for DiGiorno and a Game of Thrones binge.”

Who could say no to that?

An important question lingers: Apart from the cringe-worthy moniker, is the dad bod an acceptable standard of health? Not aesthetically, but medically?

It all depends on you.

If you’ve got a body like Leo, Seth Rogan or Adam Sandler, a discerning doctor is likely to be less concerned with how you look today and more concerned with how you looked five years ago.

What matters is where you’ve been and where you’re headed, said Harland Holman, MD, of the Spectrum Health Family Medicine Residency Center.

BMI, waist circumference

To assess a guy’s overall level of fitness, you have to account for how his body has changed from past to present, Dr. Holman said.

“You can’t just assume from one single picture what their lifestyle is,” he said.

You need context.

Explained Holman: “So, if Leonardo had a six pack and all of a sudden he’s looking like that?”

Not so good.

“But somebody who looks like that—who had a BMI that was 50, and obviously over the last year they’ve made some pretty big changes?”

Pretty good.

Body Mass Index, or BMI, is a decent indicator of a person’s fitness.

“First thing is, we’d see where your BMI is,” Dr. Holman said. “We shoot for a BMI of between 20 and 25.”

Many online sites will calculate your BMI, which is your weight, in kilograms, divided by the square of height in meters. (A 6-foot-1 man who weighs 215 pounds, for instance, has a BMI of about 29—slightly over the recommended cutoff of 25.)

But BMI is not the Holy Grail.

“Depending on your BMI, another indicator could be your waist circumference,” Dr. Holman said.

A man of average height should have a waist circumference of less than 40 inches. Anything over that, Dr. Holman said, and it’s an indication of a possible risk for metabolic syndrome.

You could make the argument that a dad bod that’s heavy in the middle is simply cuddlier and more lovable, but that’d be the only argument you’ve got.

Excess fat around the waist indicates a higher risk for heart disease and type 2 diabetes, Dr. Holman said.

“Obviously that extra fat around the abdomen … if celebrities or media are promoting that, that’s a little concerning,” he said.

Genetics, circumstance

Substantial physical change may prove frustratingly elusive for some fellas, but that’s only because their genes are tight—so tight, they’re never letting go.

“To be honest with you, there are genetics behind weight,” Dr. Holman said.

“You don’t really have control over that,” he said. “Focus on what you have control over. What do you put in your mouth every day? What do you do every day?”

If you’re eating healthy and you’re exercising, there’s a fair chance, bad genes or good, your body will reap the benefits.

And, dad bod or not, be leery of any message that says beer and pizza are acceptable regular components of any diet.

“When people start saying that’s cool, maybe we’ve gone too much the other way,” Dr. Holman said.

Here he’s alluding to those opposing ends on that John Candy-Dwayne Johnson spectrum. There really is a happy middle. (You can have a piece of pizza and a beer once in a while; just don’t make them fixtures of your diet.)

“When everyone needed a six-pack, some people gave up trying for that,” he said. “Hopefully they would, in the media, kind of promote more healthy living instead of focusing on what the picture of the abs looks like.”

Write your history—and your child’s

There’s a good reason they call it the “dad bod.”

Once men and women procreate, those little people called children commandeer every aspect of their lives, leaving precious few moments for time-intensive exercise regimens.

“There is that weight gain that dads get,” Dr. Holman said. “It often goes along with moms gaining weight, too. You become more focused on caring for your kids than yourself sometimes.”

Dr. Holman’s advice to patients, and parents: Focus less on looks and more on healthy activities and healthy meals.

And promote the same things in your kids.

Because apart from genetics, how you look today has something to do with how you grew up.

“A lot of weight depends on what you were early on,” Dr. Holman said. “Your body kind of sets a standard weight by the time you’re a teenager.”

If a poor diet and sedentary lifestyle were hallmarks of your childhood, your journey to health in adulthood may be fraught with more pain and slower gains.

If, however, you were active as a kid—youth sports, a love of outdoors and the like— you may find it easier to bounce back as an adult, even in your later years.

“Some people feel like it’s always going to be hard work to get under that weight that your body has set as its baseline weight,” Dr. Holman said. “It’s not that you can’t overcome it. It’s just that it gets a little bit harder to overcome.”

Mind your body

So, really, do looks matter? To a degree, yes. More accurately, what matters is the measurement of your looks. Your BMI and waist circumference will play roles in what your doctor has to say about your health and fitness needs.

But your health history—your weight today versus a year ago, or two years ago—is just as important. You should celebrate steps toward better health, no matter how small, and also recognize when your health is slipping.

“If the BMI is above 30, usually I will order a blood test,” Dr. Holman said. “A common blood test checks cholesterol, diabetes and thyroid.”

That’s the introductory assessment.

“That shows how urgent it is for them to make some lifestyle changes,” he said.

If your BMI is 30 but your cholesterol level is great and you don’t have diabetes, “it’s not nearly as urgent as someone whose BMI is 30 but they’re starting to get pre-diabetes,” he said.

A normal blood sugar level is typically lower than 100. Anything greater than 125 is considered diabetes. Pre-diabetes is the range in the middle.

“There’s that gray zone between 100 and 125,” Dr. Holman said, “when people can make a huge lifestyle change and prevent getting diabetes.”

And who knows—you might also prevent the complete onset of a dad bod.