Waist–hip ratio
WHR is used as a measurement of obesity, which in turn is a possible indicator of other more serious health conditions. The WHO states that abdominal obesity is defined as a waist-hip ratio above 0.90 for males and above 0.85 for females, or a body mass index (BMI) above 30.0. The National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK) states that women with waist-hip ratios of more than 0.8, and men with more than 1.0, are at increased health risk because of their fat distribution.
Devendra Singh
A pioneer in the field of evolutionary psychology, Singh's most notable research concerned the evolutionary significance of waist-to-hip ratio (WHR). In 1993, he was the first to elucidate the concept and significance of this ratio as an indicator of attractiveness. In brief, Singh discovered that men rated women with low WHR (0.7) as optimally attractive, noting that lower levels of WHR correlated to lower risk of disease and greater fertility. Subsequent research demonstrated the cross-cultural and cross-temporal appeal of a low WHR. One of his final research papers on the topic of WHR found that the "hourglass figure" (optimal WHR) activates brain centers that drive appetitive sociality/attention toward females that represent the highest-quality reproductive partners.