Outgoing people tend to be overweight, while anxious types are more likely to be thin, according to Japanese researchers who examined the links between personality and body mass.

More than 30,000 people in northeastern Japan aged between 40 and 64 were quizzed about their height and weight, and given a personality test, according to a study published in the Journal of Psychosomatic Research this month.

The results showed that outgoing people were far more likely than other people to have a body mass index (BMI) of more than 25, a widely used definition of overweight, said Masako Kakizaki of Tohoku University, who led the analysis.

After controlling for other factors, such as smoking, men in the most extrovert category were 1.73 times more likely to be obese than their most introvert counterparts. Extrovert women were 1.53 times as likely to be obese.

People ranked as having the most anxious personalities were twice as likely as the least anxious to be underweight, or have a BMI of less than 18.5, the study found.

These results may provide clues to devising more effective measures for preventing overweight, obesity or underweight, the researchers said in their paper.