London, Sep 24 (IANS): The price of obesity may be much higher than earlier thought as researchers have found that men who are already obese as teenagers could grow up to earn up to 18 percent less than their peers of normal weight.

Previous research has shown only that obese young women pay a price when they enter the labour market.

This study shows how this pattern also emerges among men who were already overweight or obese as teenagers, but does not hold true for males who gain excessive weight only later in life.

"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," said co-researcher Paul Nystedt from the Linkoping University in Sweden.

For the study, the team compared extensive information from Sweden, Britain and the US.

The researchers analysed large-scale data of 145,193 Swedish-born brothers who enlisted in the Swedish National Service for mandatory military service between 1984 and 1997.

Tax records were then used to gauge the annual earnings of this group of men, who 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 US National Longitudinal Survey of Youth, 1979.

The results showed that obese teenage boys grew up to earn 18 percent less in adulthood.

The researchers ascribed the wage penalty partly to obese adolescents' often possessing lower levels of cognitive and non-cognitive skills.

Over-weight kids are also vulnerable to bullying, lower self-esteem and discrimination by peers and teachers.

The study appeared in the journal Demography.