C. Obtain Waist Circumference Measurement

objective

Assess person’s body fat distribution.

background

The patient’s BMI is recommended to classify overweight and obesity and to estimate relative risk of disease compared to normal weight.  WC is considered an indicator of increased disease risk for overweight patients and is the most practical anthropometric measurement for assessing a patient’s abdominal fat content before and during weight loss treatment.  Gender-specific WC cut-offs should be used in conjunction with BMI to identify increased disease risk.

recommendations

1. For screening purposes, waist circumference should be obtained in patients with a BMI < 30 kg/m² as a predictor of disease risk.  [C]
2. The waist circumference measurement should be made with a tape measure placed above the iliac crest and wrapped in a horizontal fashion around the individual’s abdomen at the end of a normal expiration.
3. Gender-specific cut-offs should be used as indicators of increased waist circumference.  [C]
• Men: waist circumference > 40 inches (102 cm)
• Women: waist circumference > 35 inches (88 cm)

discussion

The presence of excessive central adiposity, measured by WC, has been shown to be an independent predictor of weight-related comorbidities, regardless of BMI, sex, race, and ethnicity (NHLBI, 1998).  Furthermore, in some populations of patients, WC may be a better indicator of CVD risk than BMI alone (Zhu et al., 2005). 

Increased WC has been shown to be an important independent predictor of disease risk (Zhu et al., 2005).  This additional disease risk likely reflects the ability of WC to act as a surrogate for abdominal, and in particular, visceral fat (Janssen et al., 2002).  WC is defined as the length around the abdomen measured above the iliac crest (instructions on standardized measurements can be found on the NHLBI Web site http://www.nhlbi.nih.gov/guidelines/obesity/practgde.htm).  Weight loss treatment is recommended for all obese patients (BMI ≥ 30 kg/m²) regardless of WC (McTigue et al., 2003; NHLBI, 1998; WHO, 2000).  WC is incorporated as an “or” factor, because some patients with a BMI lower than 30 will have a disproportionate amount of abdominal fat, which increases their cardiovascular risk despite their low BMI (NHLBI, 1998).  In addition, decisions regarding management and progress of weight loss may be guided by the measurement of WC for all patients.

Like BMI, clinically relevant cut-offs for WC likely differ by ethnic group.