A study of different female body shape preferences found that men prefer body shapes that suggest youth.
Men from 10 countries were asked to rank a series of body shapes from most to least attractive.
Popular among all the participants was the female body shape with a BMI of 19.
This is on the borderline with being underweight.
A correlation between higher BMI and perceived lesser attractiveness was also evident.
Professor John Speakman, who led the study, explained:
Fitness in evolutionary terms comprises two things: survival and the ability to reproduce.
What we wanted to investigate was the idea that when we look at someone and think they are physically attractive, are we actually making that assessment based on a hard-wired evolutionary understanding of their potential for future survival and reproductive ability?
One of the study's authors Dr Lobke Vaanholt, also commented:
Although most people will not be surprised that extreme thinness was perceived as the most attractive body type, since this prevails so heavily in media, culture and fashion, the important advance is that now we have an evolutionary understanding of why this is the case.
The team believed the preference for a lower BMI was because it suggested a woman aged 17-20.