John Strauss of the University of Southern California finds highly educated women were more likely to have have a healthier average weight than less educated women, but the meaning of "healthier" depends on a nation's relative wealth.

For example, in the poorest country analyzed in the study -- Bangledesh -- half of the adult population is underweight and average female body mass increases with every additional year of schooling. In the wealthiest nation -- the United States -- where 1 percent of the population is underweight and obesity is a problem, more educated women weigh less.

In Mexico -- where 74 percent of the women are overweight or obese -- weight declines for every year of schooling more than five years.

However, in men, weight increases with every year of schooling in every country except the United States -- the only country where better-educated men weigh less than less-educated men.

The findings appear in the latest volume of the "Handbook of Development Economics: Volume 4."