As the obesity epidemic continues to balloon, a growing body of research shows that in general, obese workers are experiencing discrimination in the workplace — and are getting paid less than people of normal weight.

According to a new study published in the journal Demography, obese teenage men earn up to 18 percent less than normal weight peers. Researchers examined the data of 145,193 Swedish brothers enlisted in the Swedish National Services for mandatory military service between 1984 and 1997, and found that the trend was visible primarily in obese teenagers who grew up to earn less — but not necessarily in normal weight teenagers who gained large amounts of weight as they got older. Previous research only showed this wage trend affected obese women.

The authors compared the loss of money among Swedish obese teenagers to that of people who shaved three years of school off their education. “To put this figure in perspective, the estimated return to an additional year of schooling in Sweden is about six percent,” the authors said. “The obesity penalty thus corresponds to almost three years of schooling, which is equivalent to a university bachelor’s degree.”

The researchers also discovered a parallel trend among young men in the U.S. and the U.K., showing that it appears to be specific to males who were overweight teenagers. Their theory is that obese adolescents may be more likely to suffer self-esteem problems and discrimination by peers and teachers, knocking down their levels of cognitive and non-cognitive skills (meaning memory, attention, logic — and motivation, self-confidence, and persistence, respectively). Of course, this is quite a general statement — more research will need to be done to understand why men who were obese as teenagers on the whole get paid less than their normal weight peers.

The Centers for Disease Control & Prevention (CDC) state that obesity among children in the U.S. has doubled in the past 30 years, and quadrupled for adolescents.

“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,” lead author Paul Nystedt of Jönköping University in Sweden said in the press release. “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.”

The trend the study is examining isn’t exactly a new notion — it’s been referred to as the obesity wage penalty. Studies have shown that obese women experienced the most discrimination when it came to lower salaries due to their weight. “Various studies have shown that overweight people are seen as less conscientious, less agreeable, less emotionally stable, less productive, lazy, lacking in self-discipline, and even dishonest, sloppy, ugly, socially unattractive, and sexually unskilled; the list goes on and on,” Freek Vermeulen writes on Forbes, ultimately contributing to a drop in salary.

But is this stereotype truly backed up by solid evidence? Some studies have shown that obese and hypertensive men performed worse on cognitive performance tests, and research at NYU Langone Medical Center found that obese children performed more poorly on memory and spelling tasks. “Their brains are not firing on all pistons,” Dr. Antonio Convit, professor of psychiatry and medicine and director of the BODyLab, said in a press release. “The more overweight that youth are, the more they experience the medical consequences of obesity, and the greater the difficulties they have in all these areas of cognitive functioning.” Whether this is a consequence caused by physical or biological reasons — or if it’s a matter of psychological and emotional problems created by obesity stigma — is still being examined.

The Swedish study is the first, however, to identify the pattern in men. “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 authors write in the abstract.

Source: Lundborg P, Nystedt P, Rooth D. “Body Size, Skills, and Income: Evidence From 150,000 Teenage Siblings.” Demography, 2014.