Dad Bod
"Dad bod" is a real phenomenon, believe it or not. Many dads tend to gain weight after their first child arrives, researchers say. Reuters

Dads know that words cannot express seeing their first bundle of joy. But there are plenty of words to describe the sleepless nights and constant worries and fears that come with being a first-time dad. Add up all the stress of caring for a newborn, and you get something called the "Fatherhood Effect."

A new study revealed first-time dads even tend to put on a few pounds after the baby gets home. Northwestern Medicine tracked the weight of 10,253 men from their teenage years until adulthood. Each participant had his body mass index measured four times during the study -- early adolescence, later adolescence, mid-20s and early 30s. Each also was listed as a nonfather, resident father or nonresident father. Researchers looked at a group of men who were first-time dads and compared them with men who remained kid-free.

If you're a 6-foot-tall dude who's raising a kid and living with the child, the study found you gained an average of about 4.4 pounds. Raising a child but not living with them led to a weight gain of around 3.3 pounds. On the flip side, child-free men lost 1.4 pounds during the same time. Researchers eliminated age, race, education, income and other factors to determine first-time dads gained weight while nonfathers lost weight.

Aside from making a dad look a bit soft, the extra weight can have huge implications for the future. "The more weight the fathers gain and the higher their BMI, the greater risk they have for developing heart disease as well as diabetes and cancer," the lead author, Dr. Craig Garfield, associate professor of pediatrics and of medical social sciences at Northwestern University's Feinberg School of Medicine, said in a statement. It's no longer about you, but about your family.

Luckily, a little extra weight is pretty easy to combat -- but it requires doing all the boring stuff. Eat better, take some time to exercise and talk to your child's pediatrician. Sure, your kid may not be able to finish his meal, but that doesn't mean you should. A pediatrician will tell you all you need to know about your child's health -- and also advise you about your own nutrition, Garfield said.

So, if you happen be newly married and a first-time dad, get ready to learn what "dad bod" is all about.