Human height has increased over the past century due to better nutrition and health, but the increase has not been equal between men and women, according to a new study by CNN.

Research published last week in the journal Biology Letters found that men have grown twice as tall and heavy as women.

A team of researchers from Italy, the United States and the United Kingdom analyzed 2003 data from the World Health Organization (WHO) on the height and weight of more than 100,000 people from 69 countries. The authors also used data from the Human Development Index (HDI).

The research team found that for every 0.2 point increase in HDI, women's height increased by approximately 1.68cm, and men's by 4.03cm. Average weight also increased by 2.70kg for women, and 6.48kg for men.

This trend is also confirmed by evaluating data from the World Bank's Gini Index - a measure of national income inequality - for 58 countries from 2000 to 2006. A higher Gini coefficient indicates a country with more income inequality.

High inequality is also associated with lower height and weight. According to the study, each unit increase in Gini was associated with an average height loss of about 0.14cm in women and 0.31cm in men, and an average weight loss of about 0.13kg for women and 0.39kg for men.

Study co-author Lewis Halsey, an environmental physiologist at the University of Roehampton in the UK, believes that the difference in height growth rates between men and women is due to sexual selection. According to Halsey, men who were previously taller and heavier tended to be healthier, which helped them outnumber other men in approaching more women, thereby passing on the genes for superior height.

Even today, “women still tend to prefer taller men,” Halsey said. Women’s height, on the other hand, is seen as less important, with men less likely to say, “Oh, I just like tall women.”