Scientists can now confirm that the father body is actually for real. A massive study conducted by experts from Northwestern University's School of Medicine Men involved more than 10,000 men covering 20 years to find that fatherhood increased the chance of weight gain and an increase in body mass index (BMI). The BMI is the amount of body fat against a person's height. Meanwhile, men who did not become father did not gain weight for the time span of the study.

The study, published on Tuesday in the American Journal of Men's Health, is hailed as the first of its kind. "Fatherhood can affect the health of young men, above the already known effect of marriage," Craig Garfield, who works as associated professor at Northwestern and the study's lead author, said.

"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."

Taking a closer look, resident dads or those who lived with their children, have a slight difference in their weight gain compared to those who did not. First-time resident dads gained an average of 2.6 percent compared to non-residents who gained 2 percent. This means that a six-foot resident dad is likely to gain an additional 2 kg, while a non-resident could gain 1.5 kg. A non-dad could lose half a kilogram.

Experts suggest that the increase in BMI is linked to changes in lifestyle, as fathers tend to have more responsibilities related to child-rearing and "less time to take care of yourself the way you once did in terms of exercise," Garfield said.  

The research started in 1994 and involved recording BMI measurements from 10,253 during the four life stages of men, from adolescence to the early 30s. Certain factors were also considered, such as race, education and income, among others. It was noted that BMIs changed as the men age, as well as whether or not they embraced fatherhood.

The researchers recommended the need for young dads to develop preventive strategies since a father's weight is also linked to their children's health.