You're at greater risk if you are an 'apple' - in other words, you carry your extra weight around your stomach - than if you are a 'pear' - where your excess weight is carried around your hips.
To find your waist-to-hip ratio, measure your waist at the level of your navel, and your hips around the buttocks, then divide the size of your waist by your hip size. A ratio that is greater than 0.8 in women, and 0.95 in men, suggests a higher risk of a heart attack.
The predictive accuracy of this ratio was established by testing various methods on 27,000 people. The BMI was by far the most inaccurate as it fails to take into account muscle density and other relevant factors.
Furthermore, those who were obese as judged by the waist-to-hip ratio had substantially more heart attacks than those who were obese according to their BMI (Lancet, 2005; 366: 1640-9).