Women are harsher judges than men on how weight affects other people's beauty, according to a new study.

But women are also judged more negatively for being overweight by both men and women, the researchers from the universities of Surrey and Oxford say in their report published in the journal Economics and Human Biology.

The researchers assessed how male and female interviewers scored the attractiveness of interviewees of both genders, looking at how body mass index (BMI) affects perceptions of beauty.

They found that female interviewers would judge both men and women with higher BMIs as less attractive, whereas men would judge their fellow gender much less harshly.

Professor Sonia Oreffice, of the University of Surrey, said: "This is the first study that looks at the relationship between BMI and attractiveness, from both gender's perspective.

"When it comes to 'beauty', being an overweight woman is judged negatively by both sexes whereas men are a lot more forgiving towards each other.

"There is plenty of research that shows how beauty is related to socioeconomic detriment, from schooling to crime to wages.

"Similar research also explores the negative correlation with BMI but what we have shown is that weight is intrinsically linked to attractiveness and that women are the harshest judges and most harshly judged.

"Perhaps BMI is not able to distinguish fat from muscular mass, and this is particularly important for male BMI."

Prof Oreffice added: "While we are not entirely surprised with the results that correlate BMI and attractiveness, what is remarkable is that gender of the interviewer makes a difference and that body size matters for wages not simply as proxy for beauty."