Waist Circumference as a Measure For Health Risks

Source: Tufts University
December 20, 2002 (Reviewed: December 16, 2004)

The National Heart, Lung, and Blood Institute recommends the use of waist circumference (WC) measurements in addition to body mass index (BMI) to identify overweight adults. The inclusion of WC cutoff points is based on evidence that abdominal (android) obesity is a greater health risk than lower body (gynoid) obesity. What is unclear is whether a high WC is predictive of health risks independent of BMI. Canadian researchers addressed this question and published their findings in a recent issue of Archives of Internal Medicine.

NHANES III Data

The researchers assessed data on 14,924 adults who participated in the Third National Health and Nutrition Examination Survey (NHANES III). Volunteers were divided into three BMI groups and two WC groups based on cut off points set by the National Institutes of Health (NIH). Men with a WC >102 cm (>40 inches) and women with a WC >88 cm (>34.5 inches) were considered to have a high WC. Less than or equal to these values were considered normal. Body mass index classifications were normal (18.5-24.9), overweight (25.0-29.9), or class I obese (30.0-34.9).

The researchers recorded the prevalence of hypertension, type 2 diabetes, dyslipidemia, and a clustering of metabolic risk factors (called metabolic syndrome or syndrome X). The Joint National Committee Guidelines on Detection, Evaluation, and Treatment of High Blood Pressure were used to detect hypertension. Type 2 diabetes was determined by the American Diabetes Association standards. Dyslipidemia and metabolic syndrome were measured according to the National Cholesterol Education Program guidelines.

High WC increased the risks

In this analysis, 1% of normal weight men had high WC, which increased their risk of type 2 diabetes. In normal weight women, though, an across-the-board risk increase - for diabetes, hypertension, dyslipidemia and metabolic syndrome - was seen in the 14% with high WC.

About 28% of overweight men and 72% of overweight women had high WC. Among obese participants, 85% of the men and 97.5% of the women had high WC. As would be expected, disease risk was greater for overweight and obese individuals, but high WC added to the problem. At BMI levels >25, high WC compounded the risk of hypertension, dyslipidemia, and metabolic syndrome in both men and women, and type 2 diabetes in women.

Cut off points to consider

The authors point out that these findings have important clinical implications, underscoring the necessity of incorporating both BMI and WC when assessing health risks. The NIH WC classification system is dichotomous, but the researchers saw a linear trend when they classified volunteers in to three categories. And, because WC increased with age, refining the WC guidelines and making them age-specific warrants further investigation.

Source

• Body mass index, waist circumference, and health risk. Evidence in support of current National Institutes of Health Guidelines. I. Janssen, PT. Katzmarzyk, R. Ross, Arch Int Med, 2002, vol. 162, pp. 2074--2079

Related Links
National Heart, Lung, and Blood Institute website
Weight loss aids people with diabetes
The Metabolic Syndrome: Time for Action!
Tool: Find Out Your BMI
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