By Linda Carroll for TODAY
New moms don't have to feel they're alone in battling the bulge. Dads gain baby weight, too, according to the first new study to look at how children affect men's waistlines.
Northwestern University researchers following more than 10,000 men from adolescence to adulthood found that fatherhood was associated with a weight gain of about 3.5 to 4.5 pounds—a 2.6 percent increase in BMI, according to the study published in the American Journal of Men's Health.
The findings came as a surprise, said Dr. Craig Garfield, the study's lead author and an associate professor of pediatrics and medical social sciences at Northwestern's Feinberg School of Medicine.
"We had done some earlier work that shows that becoming a father actually encourages people to clean up their act a little bit, eat a little better, drink a little less alcohol, smoke less if they are smokers—try to be a good role model," Garfield said.
Garfield and his colleagues scrutinized the health records of 10,253 men who had their BMI measured at four points in time during a 20 year period: early adolescence, late adolescence, mid-20s and early 30s. The researchers then checked to see how fatherhood might have affected body-mass index, or BMI.
During the course of the study, about 3,425, or about a third, of the men became fathers.
After accounting for factors known to contribute to weight gain, such as age, race, education, income, daily activity, screen time and marriage status, the researchers determined that dads who lived with their children saw a 2.6 percent rise in BMI, while those who didn't live with their kids experienced a 2.0 percent increase in BMI.
Men without kids actually dropped weight over this time period.
For a 6-foot-tall dad living with his kids, that works out to be an average gain of 4.4 pounds. For the same height dad not living with his kids, it would be an average gain of 3.3 pounds.
While that may seem to be a small weight gain, it might make a big difference if the men continue to gain weight as they age, said Dr. Eduardo Grunvald, an expert unaffiliated with the new research and medical director of the University of California, San Diego, Weight Management Program.
The findings weren't a surprise to Grunvald, who said "I see patients all the time who, when they become fathers, the first thing that happens is their exercise drops off. This study is very interesting because this hasn't been looked at before."
While men may plan to become healthier when they become dads, the whole experience may derail even the best of intentions, Grunvald said.
"When you have a child all those things go out the window," Grunvald said. "You're trying to figure out how to be a father, how to balance work and sleep. Your stress goes up. You've got less time to be physically active. All those things influence your overall lifestyle."