How are waist circumference and hip circumference measured and what are the implications for health risk assessment?

Waist and Hip Circumference Measurement Technique and Clinical Implications

Measurement Technique

Waist circumference should be measured at the level of the iliac crest with the patient standing, using a measuring tape positioned horizontally around the abdomen, ensuring the tape is snug but does not compress the skin, with the measurement taken at the end of a normal expiration. 1

Standardized Waist Circumference Measurement Protocol

• Locate the upper hip bone and the top of the right iliac crest as the anatomical landmark 1
• Position the measuring tape in a horizontal plane around the abdomen at the level of the iliac crest 1
• Ensure the tape is snug but does not compress the skin and is parallel to the floor 1
• Take the measurement at the end of a normal expiration 1
• The patient should be standing and wearing light clothing 2

Hip Circumference Measurement

• Measure hip circumference at the point of maximum circumference around the buttocks for accurate waist-to-hip ratio calculation 3
• Use the same horizontal positioning technique as waist measurement 3

Alternative Measurement Sites (Less Preferred)

While the iliac crest is the recommended site, research has identified that measurement at the umbilicus shows the greatest sensitivity for detecting cardiometabolic risk factors (75-89% in women, 48-59% in men), while the minimal waist site provides the best specificity (52-79% in women, 77-88% in men) 4. However, the iliac crest remains the standardized site for clinical consistency 1, 2.

Clinical Thresholds for Risk Assessment

Waist Circumference Cut-Points

Elevated waist circumference is defined as ≥40 inches (≥102 cm) in men and ≥35 inches (≥88 cm) in women, thresholds that identify individuals requiring weight reduction interventions. 1

• Action Level 1 (no further weight gain): ≥94 cm in men, ≥80 cm in women 5, 6
• Action Level 2 (weight reduction recommended): ≥102 cm in men, ≥88 cm in women 1, 5, 6
• For Asian populations, lower cut-points apply: ≥90 cm for men and ≥80 cm for women 2, 5

Waist-to-Hip Ratio Cut-Points

The waist-to-hip ratio identifies high cardiovascular risk at ≥0.95 for men and ≥0.80 for women. 5

• WHR carries the most important prognostic information for cardiovascular and all-cause mortality, particularly in women 3
• Men and women who died of cardiovascular disease had greater WHR at baseline compared to survivors 3

Clinical Implications for Health Risk Assessment

Cardiovascular and Metabolic Risk Stratification

Increased waist circumference has been associated with increased cardiometabolic and atherosclerotic cardiovascular disease (ASCVD) risk, and central adiposity captured by waist circumference may be missed when BMI is used as the only measure of obesity. 1

• Waist circumference measurement is recommended in all patients with BMI <35 kg/m² to capture central adiposity that BMI alone may miss 1
• Combining waist circumference and BMI provides the best approach for assessing obesity-related risk 1
• Waist circumference is needed for the diagnosis of metabolic syndrome 1

Superiority of Waist-to-Hip Ratio for Mortality Prediction

WHR provides superior prediction of cardiovascular mortality compared to waist circumference alone or BMI, particularly when assessing risk across ethnically diverse populations. 3

• WHR adjusts for ethnic differences in body shape, providing more uniform cardiovascular risk assessment across racial groups than BMI or waist circumference cut-points alone 3
• In patients with chronic kidney disease, WHR (but not waist circumference alone) was associated with cardiac events after adjusting for demographic factors, lifestyle characteristics, baseline CVD, and CVD risk factors 3
• WHR was strongly and independently related to incident type 2 diabetes in both men and women 3

When to Prioritize Each Measurement

For cardiovascular mortality risk stratification and assessment in chronic kidney disease patients, measure WHR as the primary anthropometric assessment. 3

• For routine obesity screening and treatment eligibility decisions, use BMI to categorize patients, then add waist circumference for metabolic risk refinement 3
• For ethnic minority populations, WHR provides more uniform risk assessment across racial groups 3
• For high-volume screening settings where simplicity is paramount, waist circumference alone is acceptable 3

Common Pitfalls and Caveats

Measurement Accuracy Concerns

• Waist circumference thresholds may not have the same clinical utility at all anatomical locations of measurement 4
• Ensure consistent use of the iliac crest landmark to avoid misclassification 1, 2
• WHR requires accurate measurement of both waist and hip circumferences, which can be technically challenging and time-consuming 3

Population-Specific Considerations

• BMI should be interpreted with caution in persons of Asian ancestry, older adults, and muscular adults 1
• Ethnic differences in waist circumference thresholds associated with cardiometabolic risk have been reported 1
• Current waist-to-hip ratio cut-off points may not be appropriate for women, older adults, and certain racial or ethnic groups 5
• Populations from South Asia may have higher percentage of body fat and visceral adipose tissue at lower waist-to-hip ratio and waist circumference values 5

Clinical Limitations

• Waist circumference thresholds are not reliable for patients with BMI >35 1
• The American Heart Association does not recommend routine WHR use in general practice due to measurement complexity, despite its superiority for mortality prediction 3, 5

Treatment Implications

Decreases in waist circumference are a critically important treatment target for reducing adverse health risks for both men and women. 7

• Clinically relevant reductions in waist circumference can be achieved by routine, moderate-intensity exercise and/or dietary interventions 7
• Weight loss of 5% to 10% of initial weight through comprehensive lifestyle intervention improves blood pressure, delays onset of type 2 diabetes, improves glycemic control, and improves lipid profiles 1
• Comprehensive lifestyle intervention produces on average 8 kg of weight loss (5% to 10% of initial body weight) in the short term (≥6 months) and intermediate term (6 to 12 months) 1