A LINK between less body weight and attractiveness is due to an evolutionary preference for youth, according to research by University of Aberdeen academics.

Scientists have tested a theory that women with a body mass index (BMI) of 24 to 25 would be deemed most attractive based on a mathematical model.

The model looked at the relationships between levels of obesity and the future risk of mortality from all causes, and the relationship between obesity and the future possibility of having children.

Aberdeen researcher Lobke Vaanholt said the study showed thinner women, with a BMI of 17-20, were rated most attractive.

Dr Vaanholt said: “There is a lot of interest around why people become obese and one theory is this may be connected to evolution.

"Historically, overweight people were better able to survive famine.

"We predicted there was an optimal level of fatness to survive famine but not have a detrimental effect on health.”

Dr Vaanholt said researchers showed a series of photos of women’s bodies to 10 study groups around the world – which equated to more than 1,000 people – to test the theory.

Participants were shown 21 image cards in total, with the women’s faces hidden from view.

Each woman had a different level of body fatness and participants were asked to reorder them from least to most attractive.

She said: “We asked people to rate the images of different levels of fatness for attractiveness, with four groups in Africa, three in Asia and three in Europe.

"In all the groups people preferred the thinnest images, which didn’t agree at all with the model we had used to predict attractiveness.

"People generally associated a thinner body with a younger age.”

Participants judged the overweight bodies to be older and thinner to be younger.

Dr Vaanholt said age is itself a strong indicator of evolutionary fitness, suggesting we find thinness in females so attractive because we equate it with youth.

She said: “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 study only shows one element of attractiveness and, of course, many other factors come into play in real life, such as personality and facial expression.”

Scientists from the University of Aberdeen worked as part of an international collaboration co-ordinated by the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences in Beijing.

The study was co-ordinated by Professor John Speakman, of the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, and the Institute of Biological and Environmental Sciences at the University of Aberdeen. (Evening Express)