In a study published this week in the American Journal of Men's Health, researchers found that when men had children they gained on average between 3.5 to 4.5 pounds. For the men who have remained childless, they tend to lose weight by an average of 1.4 pounds.
The researchers followed more than 10,000 men, who had their BMI measured four times from early adolescence to their early 30s. Researchers found that when men had children their BMI tended to increase, even in fathers who didn't live with their children.
In the study, a typical 6-foot-tall dad gained an average of 4.4 pounds if he lived with his children. Even fathers who didn't live with their children gained approximately 3.3. pounds.
Among men, who remained childless, the average 6-foot-tall man in the study actually lost weight during the same period of time, dropping an average of 1.4 pounds.
What's more, Garfield said, men packed on these fatherhood-related pounds in addition to the weight gain usually seen as a result of being married.
Lisa Cimperman, a clinical dietitian at University Hospitals Case Medical Center in Cleveland, said that the study might reveal how men's responsibilities have shifted at home if they are taking on more child rearing duties with their partners.
"We have less time for exercise and less time to consider food choices or healthy food choices," Cimperman said of new parents. "It comes with stress often, potentially these stress actors are causing the weight gain as well."
She said that there have been a lot of research on how pregnancy and motherhood affects women's health, but this new study will give welcome insight on how fatherhood can affect men and how health providers can start to target them.
"This is a group that tends to not seek out regular preventative medical care, so perhaps we need to look at this group," said Cimperman, citing the relative lack of resources geared towards new dads. "How often do we see Mommy and Me exercise groups?"
The authors of the study theorized that pediatricians could help by advising new dads on healthy living when they bring their children in for check-ups.
Cimperman also said it's also key to understand how parenthood affects parents' health, since a their weight gain can affect their children's health.
"One of the reasons why this is important is we know that parent's body weight affects children’s body weight," explained Cimperman. "Children who have normal weight parents are more likely to be normal weight themselves."