Waistline Circumference More Accurate than BMI to Measure Obesity

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The gold standard for measuring obesity is Body Mass Index (BMI), a formula that calculates an individual’s weight to their height squared.  BMI is not a perfect measure but it gives an strong indication whether a person is overfat. New studies indicate that waistline circumference measurements may be more accurate at assessing obesity than BMI.

Tape Measure Woman Waistline Healthy Living


Body Mass Index (BMI)

They say people get wiser as they age, but new statistics show that people also get wider as they age.  Current statistics show that almost 40% of men and women are becoming obese as they age. Researchers from the University of Glasgow assessed data from the Health Survey of England and the Scottish Health Survey comparing two periods of time, 1994-1996 and 2008-2010. Researchers looked at BMI and waist circumference changes for both men and women during the two periods. Any significant changes between the two periods were documented and recorded.

BMIs above 25 are categorized as overweight.  The study showed that individuals with BMIs above 25 increased significantly.  Average BMI for all ages and both sexes in England and Scotland increased as well. 

Anyone with a BMI greater than 30 is categorized as obese.  Between the two periods, researchers saw an increase of 5-15% on average when comparing the number of adults with a BMI greater than 30. Researchers also looked at the different age groups.  If we take a magnifying glass and examine the older populations between the two periods, it is the elderly that is becoming obese.  With the 60-70 age group, over 35% of both sexes were obese.

Between the two countries, which one is fatter?  Researchers also compared the differences between the two countries.  Between the two periods, English young men with BMIs greater than 30 was 10.7% compared to the 12.7% in Scottish young men.  Similar results were seen in the women. 17.8% of English women and 20.1% of Scottish women showed BMIs greater than 30. Although the percentages are similar, the Scottish young men more than tripled their numbers, while the English young men doubled their numbers.

Waist Circumference

As noted before, BMI is not an exact measure.  Sometimes there are discrepancies between BMI and waist circumference.  Often, if BMI is high then waist measurements are also high.  Researchers noticed that some adults would have a normal BMI (18.5-25) but a large waist circumference.  Sometimes the BMI doesn't indicate that the individual is actually unhealthy due to the large wasit circumference.  What is the significance of having belly fat or a large waist circumference?  Belly fat equals increased  risk of type 2 diabetes, cardiovascular disease and death.

Harvard School of Public Health explains the benefits of doing waist circumference. In practice it is much simpler and easier to do than BMI calculation.  Also, there are several studies that suggest abdominal fat is the most accurate predictor of health risk. Abdominal obesity for women is 35 inches and 40 inches for the men. Numbers in these high digits found it was significantly associated with an increased risk of type 2 diabetes, cardiovascular disease and death.  This is even after calculating body mass index (BMI).

In the Nurses’ Health Study, the largest and longest study on abdominal obesity, researchers found the women who reported the highest waist sizes more than doubled the risk of dying from heart disease.  Similar findings were found relative to cancer.  With every added inch around your waist, you increase your risk for heart disease and cancer.

Often physicians are not required to do a waist circumference measurement, but it is a simple task that can be done at home.  Are you curious about your waist measurement?  There are three areas where you can measure waist circumference: natural waist, belly button, or narrowest point of the midsection.  Whoever takes the measurement should document placement in the patient's record to be sure accurage follow up readings.   

All 44,000 volunteers in the Glasgow study started healthy and measured normal in their waist size. The overall number of people with large waistlines increased significantly between the two periods. People with the largest waist circumference, 40 inches for men and 34.5 inches for women, increased from 30 to 70 percent between the two periods.

Waist sizes grew significantly more in Scotland versus England.  In young men, large waist circumference grew four-fold to 12.7 percent and nearly five fold in women (28 percent).  While waist sizes grew significantly, the BMIs for particular age groups did not match up.  Often BMIs would indicate the patient was healthy, but the belly fat or obese waistlines demonstrated they were unhealthy.

Researchers conclude that waistlines measurements better identify obese and unhealthy patients.



International Journal of Obesity

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