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Male students at St Andrews University were asked to rate female faces for attractiveness and health.

The study found that girls with an average weight and build were ranked as being the most attractive and healthy.

Researchers said the findings sent out a strong message to young women who believe being underweight is considered to be attractive.

The research was carried out by a team from the university's Perception Lab, who asked 84 female students a variety of questions on their health, took their blood pressure and photographed them.

The photographs were then shown to a group of male students who were asked to rate them for health, attractiveness and weight.

Professor David Perrett, who supervised the project, said: "In our study, people in the normal weight range were judged healthier and more attractive than under or overweight individuals.

"This sends a strong message to all the girls out there who believe you have to be underweight to be attractive.

"The people making judgments in our study were all between the ages of 18 and 26 and they did not rate underweight girls most attractive. They preferred normal weight girls."

Lead researcher Vinet Coetzee said although people often often remark on how healthy or unhealthy someone looks, it can be very difficult to say precisely how we know this.

'Already suffering'

She added: "Scientists have been trying to answer this question for decades, and have made many breakthroughs in our understanding of health and attractiveness, but until now they have tended to overlook the influence of weight."

Ms Coetzee said students who were rated as being overweight reported more frequent and longer-lasting cold and flu bouts, used antibiotics more frequently and had higher blood pressure than the students who were considered normal weight.

"Even at this young age, their health was already suffering because they were overweight, and what is more, other people can spot this in their face," she added.

The findings have been published online by the scientific journal Perception.

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