Beijing: Researchers finally revealed why men want slim women as their life partners. Study says, slimness in females symbolizes youth, fertility and lower risk of disease thus they appear more attractive to men and shows promise in producing a healthy young ones apart from leading a healthy and happy life. The study was lead by the researchers from the University of Aberdeen along with the Institute of Genetics and Developmental Biology at the Chinese Academy of Sciences in Beijing. For the study, researchers constructed a mathematical model on the relationship between obesity with the risk of mortality in near future and with the possibility producing children. After analyzing the mathematical model, researchers predicted that participants would rate females with BMI between 24 and 24.8 as most physically attractive. After this, all the participants were shown 21 images of females with variable body fatness in random order and were asked to rearrange the images with most to least attractive. Almost all the participants including male and female rated images similarly. They found the thinnest female in the image with BMI 19 as the most attractive while attractiveness decreased with increasing BMI. Female with BMI 30 was rated least attractive. Researchers further noted that when age was included as one of the factor in the mathematical model then optimum BMI for most attractive females fell to somewhere between 17 and 20, which similar to what participants said in the study. Thus, study authors concluded that we find thinner females more attractive because we relate it with youth that has highest fertility rate and minimum risk of any future disease. Average BMI of a girl aged between 18-20 years lies between 17 -20. Study author Lobke Vaanholt said that the study will not surprise most of people as they see skinny females in media or in fashion and find them attractive, however, the study gives an insight in an evolutionary understanding of why we think women attract us more.