February is American Heart Month and a great time to take a moment to evaluate your risk for cardiovascular disease. One quick way to assess your risk is to grab a tape measure. According to a recent study reported in Lancet, your waist-to-hip ratio, determined by dividing your waist measurement by your hip measurement, is three times more effective at predicting cardiovascular risk than using Body Mass Index, or BMI, the commonly used ratio of weight to height.
In the INTERHEART study, a case-controlled study with 27,000 participants from 52 countries, researchers found that across both sexes and among most ethnic groups, the risk of cardiovascular disease increased continuously as the participant’s waist-to-hip ratio increased. In fact, study participants in the highest fifth of waist-to-hip ratios were 2.5 times more likely to have a heart attack than those in the lowest fifth. After analyzing the data from the study, researchers concluded that a large waist size, which generally indicates large amounts of abdominal fat, appeared more harmful, while a larger hip size seemed less harmful.
These findings reinforce the importance of a person’s body shape in determining risk factors for certain chronic diseases. Typically a person’s body shape is classified as either an "apple" or a "pear" based on the area of the body that he or she tends to store excess fat. Apple-shaped people tend to store excess body fat in their abdomen mainly around their stomach and chest. Pear-shaped people tend to store excess body fat below the waist in the hips, thighs and buttocks.
Several previous studies have demonstrated that carrying excess abdominal fat (an apple shape) increases the risk for type II diabetes, heart disease and high blood pressure. It is thought that excess abdominal fat is more resistant to the action of insulin, thereby increasing the risk for diabetes. The development of diabetes, in turn, increases the risk for heart disease and high blood pressure. Pear-shaped people, on the other hand, do not seem to have as high a risk of developing the same conditions. However, excess weight carried below the waistline may contribute to varicose veins and orthopedic problems.
To determine your body shape and help assess your risk for cardiovascular disease, calculate your waist-to-hip ratio by first measuring your waist at the smallest part and then measuring your hips at the widest part. Next, divide your waist measurement by your hip measurement. For example, a person with a 36-inch waist and 40-inch hips would have a waist-to-hip ratio of 0.9. In the INTERHEART study, waist-to-hip ratios over 0.85 in women and over 0.9 in men were found to be strongly associated with an increased risk for heart disease.
Whether you are an apple or a pear, if you are overweight or obese, consider taking action to improve your weight by eating healthfully and becoming more active. The good news is that, when "apples" lose weight, they usually lose it in their upper body, especially in the stomach, and thus lower their risk. Interestingly, "pears" also tend to lose weight in their upper body so that their overall body shape does not change with weight loss.
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by Pat Kendall, Ph.D., R.D., Food Science and Human Nutrition Specialist, Colorado State University, Cooperative Extension