AMSTERDAM -- Men who were grossly overweight at the age of 18 had nearly 50 percent less chance of being married by their 30s and 40s, an international conference on obesity heard in Amsterdam on Thursday.

The findings, which held true regardless of the men's intellectual performance or socio-economic position, could suggest that women rank a man's appearance higher than other traits when choosing a partner.

"Yes, that may be one explanation," researcher Malin Kark of the Swedish Karolinska Institute medical university, told AFP on the sidelines of the four-day gathering hosted by the European Association for the Study of Obesity.

Kark's study was conducted among more than 500,000 Swedish men born between 1951 and 1961.

It found that men who had been obese at 18 were 46 percent less likely to be married in 1991, when they were aged between 30 and 40, than men with no weight problem, and 45 percent less likely by 2004.

For men who were overweight but not obese at 18, the chances of marriage were somewhat higher -- 10 percent lower than for men of normal weight in their 30s and nine percent lower in their forties.

"We think this shows that there is stigmatization of obese young men that continues into adulthood -- in their working life and also in inter-personal relationships," said Kark.

While no information was available on the men's adult weight, other studies have found that obese adolescents were likely to become obese adults, she added.

Obesity for the purposes of the study was qualified as a person with a body mass index (the weight in kilograms divided by the square of the height in meters) of more than 30.

The World Health Organization estimates that in 2005, about 1.6 billion adults were overweight, of which at least 400 million were obese.