Several studies have shown waist size is clearly linked with heart attack, stroke and heart disease risk. U.S. government guidelines now say men should aim to have a waist 40 inches in circumference or less -- 35 inches for a woman.

The waist is measured with a non-stretchable measuring tape at the narrowest point of the torso between the bottom of the ribcage and the hip bones. Tension should be firm but not pulled so tightly as to compress the tissue underneath. The hips are measured at the widest point around the buttocks.

The waist-to-hip ratio compares an individual’s waist circumference with their hips. To calculate it, the individual’s waist circumference is divided by their hip circumference. A healthy waist-to-hip ratio of 0.8 or less is recommended for females and 0.95 or less for males.