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.
Female body shape
Many studies indicate that WHR correlates with female fertility, leading some to speculate that its use as a sexual selection cue by men has an evolutionary basis. However it is also suggested that the evident relationships between WHR-influencing hormones and survival-relevant traits such as competitiveness and stress tolerance may give a preference for higher waist-hip-ratios its own evolutionary benefit. That, in turn, may account for the cross-cultural variation observed in actual average waist-hip-ratios and culturally preferred waist-to-hip ratios for women.