Highly educated women have a healthier average weight than less educated women, but the meaning of what is 'healthier' changes with nation's relative wealth, according to a new comparison of multi-national data.
The data showed that in countries where malnutrition is prevalent, better-educated women weigh more.
However, in wealthier countries, with rapidly growing rates of obesity, better-educated women weigh less.
"As a population moves through the nutrition transition, it is the most educated, and highest income, who are the first to exit under-nutrition. They are also the first to adjust their diet and physical activity to avoid the deleterious effects of being overweight. It appears that it is women who tend to lead this transition," said John Strauss, professor of economics at the University of Southern California.
In Bangladesh, the poorest country analysed by Strauss and Duncan Thomas (Duke University), more than half of the adult population is underweight.
The study showed that average female body mass increased with every additional year of schooling in Bangladesh
On contrary, only 1 percent of people in the United States are underweight.
The researchers found that in the United States, the wealthiest country in the study, better-educated women had a lower average body mass index.
"Obesity rates rise with economic development which is troubling given the relationship between obesity and cardiovascular disease, stroke, diabetes and possibly cancer," Strauss said.
For example, the researchers found that almost twice as many women are now overweight as are underweight in China.
Also, in developing countries worldwide, women are more likely than men to be overweight or obese.
The researchers found that gender gap is largest in South Africa, where more than one-third of women are obese, as compared to about 10 percent of South African men.
However, they found that once women receive a certain amount of schooling, average body mass index (BMI) falls and they are more likely to be at a healthy weight.
"Behavioural changes have important impacts on health outcomes," Strauss said.
For instance, the average BMI of a Mexican woman, where 74 percent of the women are overweight or obese, declines every year of schooling she receives in excess of just five years.
There is a similar sharp decline in the average female's BMI in South Africa after five years of education.
Besides all this, researchers found that the US was the only nation surveyed in which better-educated men had a lower average BMI than less-educated men.
While in every other country, the average male body mass increased with every additional year of schooling.