Dad Bod Is Explained By Science In a New Study

4 minute read

According to Clemson student Mackenzie Pearson, who wrote a viral essay essay on the appeal of the dad bod, it’s a physique that’s a “nice balance between a beer gut and working out,” the result of going to gym but indulging in a few pizzas once in a while and being okay with that. (Think John Hamm, and Chris Pratt before he went Jurassic.)

And according to scientists, Pearson and her demographic have pretty much nailed it. The source of that “more human, natural and attractive” body is unique to fathers and can be traced to simply having kids.

In a study published in the American Journal of Men’s Health, Dr. Craig Garfield, a pediatrician at Northwestern University Feinberg School of Medicine and his colleagues dove into a database of 10,263 men beginning when they were 12 years old and followed them for up to 20 years. They looked specifically at how body mass index (BMI), a combination of height and weight, changed over time as the men either became fathers or did not, and for those who did, whether they were what the researchers called resident fathers who lived with their children, or non-residents who lived separately.

Read more Why We Accept ‘Dad Bod’ on Rich Men

Whether or not they lived with their kids, becoming a father was linked to around a four pound increase in weight over the study period, while remaining child-free was associated with a 1.4 pound weight loss for a six-foot-tall man.

“It’s a unique look at the influence that a social phenomenon, becoming a father, has on a biological marker, namely BMI,” says Garfield. “It really plants fatherhood as a potential social determinant of health for men.”

That’s a critical finding, especially since men, and in particular young men, are typically less proactive about taking care of their health. Garfield notes that while many men will quit smoking and drink less and otherwise try to become healthier when they become fathers, there may be other factors associated with caring for kids that counteract those good intentions, such as being surrounded by more kid-friendly, high calorie foods and snacks, as well as their leftovers.

“From my own point of view, we wouldn’t have as many pizzas in the house if the kids weren’t around, and we wouldn’t have the brownies my wife makes if the kids weren’t around,” says Garfield. “Having kids around changes not only the food in the house and what is available to you for meal, but also for snacks. It also changes whether you are able to find time to get out and exercise and get enough sleep and take care of yourself.”

Read more Dadbod, Mombod and Our Pretty Bad Bod Prob

Dads, of course, are not alone in experiencing these effects of parenthood. But this is the first study to tease out specifically the effects of fatherhood on weight gain over time. Since men are less likely to be seeing doctors regularly, if they are joining their partners during prenatal visits or pediatric visits, says Garfield, those are good opportunities to talk to them about their own eating, exercise and sleep habits to make them aware of the sneaky way that pounds can creep up on dads and potentially affect their health (even if the look seems to have its own kind of physical appeal).

Read next: For the Dad Who Is Confident About How He Looks in Swim Trunks

Listen to the most important stories of the day

QUIZ: Should You Eat This or That?

Which is better for you: A 1/2 cup of ice cream or 3 scoops of sorbet?
Which is better for you: Half cup of ice cream or 3 scoops of sorbet?Getty Images (4)
Answer: A 1/2 cup of ice cream
Answer: A half cup of ice cream If you eat what you’re craving, you’re more likely to feel satisfied and eat less. And scoop for scoop sorbet contains twice the sugar with none of the filling dairy protein and fat.Getty Images (5); Gif by Mia Tramz for TIME
Which is better for you: Real butter or spray on fake butter?
Which is better for you: Real butter or spray on fake butter?Getty Images; Tara Johnson for TIME
Answer: Butter
Answer: Butter Serving size for spray butters (even low-calorie ones) are around a 1/3 second spray. What on earth does that mean? You're better off using a small amount of real butter as opposed to guessing how much you're using of the mystery melange of up to 20 ingredients.Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: A sirloin burger or a turkey burger?
Which is better for you: A turkey burger or a sirloin burger?Getty Images (2)
Answer: Sirloin burger Restaurant turkey burgers are often made with dark meat and the skin, so they’re not necessarily better for you (and for the record, they aren't low-fat). You can get a sirloin burger that’s 95% lean meat and gives you 20 g of protein. Just be careful with the toppings.Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: Almonds or pretzels?
Which is better for you: Almonds or pretzels?Getty Images (2)
Answer: Almonds
Answer: Almonds Almonds are high in protein, fiber and fat and will keep you feeling fuller longer. Give high-sodium pretzels about an hour and you'll feel hungry again thanks to the high-carb no-fat or protein content.Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: Eggs or Special K?
Which is better for you: Special K or eggs?AP; Getty Images
Answer: Eggs
Answer: Eggs In the morning, you want a meal that will fill you up. Eggs offer protein and fat for satiety, but Special K cereal really only offers carbs and, well, air. If you want carbs to kick off the day, you're better off pairing eggs with a slice of 100% whole grain toast. Getty Images (1); Gif by Mia Tramz for TIME
84505234
Which is better for you: Fat free salad dressing or regular salad dressing?Tara Johnson for TIME
Answer: Regular salad dressing
Answer: Regular salad dressingTo absorb fat soluble vitamins like Vitamins E and K in vegetables you need to consume them with a fat to aid nutrient absorption. Fat-free dressing, meanwhile, is low-calorie but gets its flavor from added sugar and salt.Tara Johnson for TIME (5); Gif by Mia Tramz for TIME
Which is better for you: A low fat cookie or dark chocolate?
Which is better for you: A low fat cookie or dark chocolate?Getty Images (2)
Answer: Dark chocolate “People tend to believe fat free is calorie free,” says Keri Gans, a registered dietitian in New York City. “Go for the real thing.” Fat free cookies may be lower in fat, but higher in other ingredients like sugar. Try a nice piece of dark chocolate for those antioxidants.
Answer: Dark chocolate “People believe fat free is calorie free,” says Keri Gans, a registered dietitian in New York City. “Go for the real thing.” Fat free cookies tend to be high in carbs, sugar and fake sugar. Try a nice piece of antioxidant-rich dark chocolate instead.Getty Images (2); Gif by Mia Tramz for TIME
Which is better for you: Low fat Greek yogurt or 100 calorie Yoplait yogurt?
Which is better for you: Low fat Greek yogurt or 100 calorie Yoplait yogurt?Tara Johnson for TIME
Answer: Low fat Greek Yogurt
Answer: 2% Greek YogurtA little fat is good in the morning to keep you full—plus it has upwards of 17g of protein per container. Fat-free "fruit" yogurt is high in sugar—7 to 10 g per serving—and lower in protein.Tara Johnson for TIME (2); Gif by Mia Tramz for TIME

More Must-Reads from TIME

Contact us at letters@time.com