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.
Waist
The waist-hip ratio equals the waist circumference divided by the hip circumference. Practically, however, the waist is usually measured at the smallest circumference of the natural waist, usually just above the belly button. In case the waist is convex rather than concave, such as is the case in pregnancy and obesity, the waist may be measured at a vertical level 1 inch above the navel. It is important to note that variables such as posture significantly influence the measurement of the waist, and therefore any measurements for a group need to maintain a constant posture between the subjects.