September 17, 2019
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It’s not about body mass index anymore: Know your waist-height ratio

For decades, body mass index has been the tool used by medical professionals to indicate the level of overweight or obesity, which in turn is believed to be associated with mortality risk. BMI is calculated by taking one’s weight in kilograms and dividing it by the square of one’s height in meters. What BMI fails to identify, however, is the distribution of fat. In recent years, a new indicator has become increasingly associated with cardiometabolic risk. Measuring the ratio of someone’s waist to their height is a better predictor of their life expectancy than BMI.

According to Dr. Margaret Ashwell, whose work on the subject dates back to at least the mid-’90s, measuring someone’s waist is important because it accounts for levels of central fat that accumulates around the organs and is closely linked to conditions such as stroke and heart disease.

The team working with Ashwell, who analyzed the health of 300,000 people, found that a waist measurement less than half that of height was a better predictor of high blood pressure, diabetes and cardiovascular events like heart attacks and strokes than body mass index. Keeping your waist circumferences to less than half your height can help increase life expectancy for every person in the world, according to Ashwell.

The researchers compared the life expectancies of groups of people at different waist-to-height ratios and were then able to calculate how many years of life were lost as their waistlines increased. For example, a 30-year-old man with a waist-to-height ratio of 0.8, representing the largest one in 500 men, could lose 17.7 years of life because of size. A woman age 50 with the same ratio, represented about one in 150 women of the same age, would lose 8.2 years of life.

By measuring waist-to-height ratio, it is thought that your doctor is getting a much earlier prediction that something is going wrong, and then the patient can be encouraged to do something about it. Self-assessment of height is usually pretty accurate and the measurement of waist circumference just requires a tape measure. Waist-height ratio can be used for men, women and children of all age groups and ethnicities.

I think most people will be much more willing to have their waist circumference measured rather than step on scales. Take a moment, measure your height then measure your waist circumference. Is your waist circumference less than half of your height? If not, work at losing a few pounds a little at a time. Remember that gradual behavior changes work best.

Start by cutting back by 250 calories per day. If you drink two sodas per day, cut back to one. If you don’t get much exercise, start by walking just 10 minutes a day and gradually increase to 30. Recent research has shown that exercise is a better antidepressant for some people than medication.

If you need assistance in making changes in your diet, ask your doctor for a referral to a registered dietitian.

Georgia Clark-Albert is a registered dietitian nutritionist and certified diabetes educator at Penobscot Community Health Care in Bangor. She provides nutrition consultant services through Mainely Nutrition in Athens. Read her columns and post questions at or email her at


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