Obese teenagers are more likely to earn 18 percent less in adulthood than their normal weight peers, according to a study led by the Lund University.

Previous studies showed evidence connecting body size during childhood and adolescence with bullying, lower self-esteem and discrimination by peers and teachers. Past research also highlighted that obese young women may face discrimination in the labor market.

This is the first study to show the association among men who were already overweight or obese as teenagers. But, the link does not exist for males who gain excessive weight later in life.

For the study, the researchers analyzed data of 145,193 Swedish brothers that included information about their cognitive (such as memory, attention, logic and reasoning) and non-cognitive skills (such as motivation, self-confidence, sociability and persistence), which can affect their productivity. The researchers then used tax records to measure participant's annual earnings when they were between 28 and 39 years old in 2003.

The Swedish results were further compared with data from the British National Child Development Study and the U.S. National Longitudinal Survey of Youth, 1979.

"To put this figure into perspective, the estimated return to an additional year of schooling in Sweden is about six percent. The obesity penalty thus corresponds to almost three years of schooling, which is equivalent to a university bachelor's degree," the authors said in a press release.

The researchers urge lawmakers to introduce policies and programs that target overweight and obesity problems that are common among low-income households. It could lower disparities in child and adolescent development and socio-economic inequalities. Plus, such programs can decrease persistent patterns of low income across generations.

"Our results suggest that the rapid increase in childhood and adolescent obesity could have long-lasting effects on the economic growth and productivity of nations. We believe that the rationale for government intervention for these age groups is strong because children and adolescents are arguably less able to take future consequences of their actions into account," Paul Nystedt of Jönköping University, said. "These results reinforce the importance of policy combating early-life obesity in order to reduce healthcare expenditures as well as poverty and inequalities later in life."

The finding is published in the journal Demography.