Serviente, Corinna; Sforzo, Gary A. Ph.D., FACSM
Waist circumference (WC) was recognized as an important and useful measure at the 2012 American College of Sports Medicine’s (ACSM) Annual Meeting when Jean-Pierre Després, Ph.D., of the Quebec Heart and Lung Institute presented the D.B. Dill Historical Lecture on “Adiposity, Fitness, and Cardiometabolic Health: The Tale of the Tape.” ACSM, American Heart Association (AHA), National Heart Blood and Lung Institute (NHLBI), National Institutes of Health (NIH), and International Diabetes Federation (IDF) agree that WC should be used to screen for cardiometabolic disease risk. Each of these leading international organizations includes WC in screening guidelines; however, there is no consensus on the most appropriate measurement technique. This makes using WC measurement confusing for exercise professionals and other allied health care workers. ACSM and several major organizations recommend applying one set of WC cut points (e.g., men, >102 cm; women, >88 cm) to assess risk; however, the practice of applying these values across different measurement sites, ages, and ethnicities should be carefully considered. In fact, as we will discuss, there is reason to believe that using these accepted threshold values can lead to misclassification of cardiometabolic risk. It is not unusual to question the results of a medical screening tool, and even highly trusted devices, such as an electrocardiogram (ECG), can provide faulty results (false-positives/negatives). Similar complications and potential errors need to be addressed for any widely applied screening tool, including WC. This article will highlight the importance and utility of WC measures, discuss measurement sites and health risk cut point values, and provide clinical recommendations for using WC. In addition, the need for more research on the topic of WC will be addressed.
WHY DOES WC MATTER?
In 2011, the AHA published a consensus statement on how to assess adiposity (4). The AHA highlighted the relationship between excess adiposity and health concerns, citing WC as a good measure of abdominal adiposity. Abdominal adiposity is a cardiometabolic disease risk factor (12,13,25), along with others such as smoking, hypertension, and age (6). WC provides a surrogate estimate of visceral adipose tissue (VAT), andVAT puts a person at risk for cardiometabolic disease (4,12).Highly accurate measurement of abdominal adiposity isaccomplished using computed tomography (CT), magneticresonance imaging (MRI), or dual x-ray absorptiometry (22,27); however, these are expensive and impractical for use in many clinical settings. Alternatively, WC measurement is an inexpensive and time-efficient way to evaluate abdominal adiposity. Harris et al. (9) concluded that WC measurement correlated strongly with total abdominal fat in their sample of more than 2,800 men and women. WC does not distinguish between VAT and subcutaneous adipose tissue (SAT) (3,27). WC, however, provides a better estimate of VAT than other popular anthropometric measures, such as waist-to-hip ratio (WHR) and body mass index (BMI) (23). WHR compares the ratio of waist girth to hip girth and is used to estimate body fat distribution. Great WHR scores (>0.86 and 0.95 for young women and men, respectively) indicate too much abdominal fat, which is linked to a high health risk (1). BMI compares height with weight (kg/m2) and is used as a preliminary indicator of body composition (1). When BMI scores are high (>30), it may signal obesity with an associated risk of cardiovascular disease. BMI is not intended to estimate VAT. However, VAT is a key indicator of cardiometabolic disease risk, and WC provides insight into VAT.
VAT is fat storage occurring at highly undesirable sites such as the liver, pancreas, and heart and, when excessive, may indicate an inability to store subcutaneous fat (6). Genetics also may play a role in predisposition to abdominal adiposity (13). Fat stored viscerally presents many negative health consequences. Such fat deposition (e.g., in the mesentery and omentum) can negatively affect liver function (5). Excessive VAT also can lead to diminishing insulin function and increasing risk of diabetes and atherosclerosis (6). Production of inflammatory agents (e.g., C-reactive protein) also occurs with VAT and is associated with an increased risk for myocardial infarction (6). Finally, with excessive VAT, other blood-borne factors (e.g., angiotensinogen and cortisol) are produced in great amounts, potentially contributing to the development of cardiometabolic diseases (6,13). In summary, it is well understood that high amounts of VAT enhance the risk for cardiometabolic diseases, and WC provides a simple and useful estimation of VAT (3).
Additional value for WC measurement is apparent when looking at data from the Third National Health and Nutrition Examination Study (NHANES III). Using NHANES III data, a team of researchers (12) determined that WC has clinical utility in predicting diabetes and cardiovascular disease. They analyzed data from 5,882 subjects grouped by gender into WC tertiles (low, medium, and high categories). It was found that a medium or high WC, for either gender, strengthened the prediction of diabetes beyond that predicted by BMI and metabolic risk factors (e.g., blood pressure, lipoproteins, and glucose) (12). These results, from a large-scale national health survey, are difficult to ignore and confirm the clinical utility of measuring WC.
HOW SHOULD WC BE MEASURED?
Despite consensus that WC is an indicator of cardiometabolic risk, a debate remains as to the appropriate site for measurement. Commonly used sites include the umbilicus, superior to the iliac crest, the minimal waist (i.e., narrowest point), below the lowest rib, and the midpoint between the lowest rib and the iliac crest (Figure). WHO recommends using the midpoint between the lowest rib and the iliac crest (30). ACSM and Anthropometric Standardization Manual (17) suggest the minimal waist, and the NHLBI (20), the NIH (21), and AHA (4) recommend the point superior to the iliac crest. Other organizations, such as the IDF (11), and the 2001 report by the National Cholesterol Education Program (7) encourage using WC but offer no site recommendation. There are advantages and disadvantages to using the sites suggested by each of these major professional organizations, as described in Table 1.
DOES SITE MATTER?
It is evident that there is confusion as to the clinical utility of each particular WC measurement site. Two main issues to be reconciled before determining the best site for WC measurement are 1) which site has the greatest intratester and intertester reliability? and 2) which site provides the best estimate of VAT and therefore cardiometabolic risk? Several studies haveshown that reliability ofWC is generally good across all WC measurement sites (10,14,18,28). This means that, whether using the ACSM-recommended minimal waist or AHA-recommended iliac crest, trained professionals taking the measurement on the same client should produce similar results. These findings also demonstrate that WC measurements are reliable when performed repeatedly by a single trained clinician. Despite this reliability, it is an unfortunate fact that WC results will vary greatly depending on which site is selected for the measurement. Measurement site selection is particularly important in women with values observed at different sites leading to disparate conclusions about risk (18). Recognizing how site selection impacts WC measurement is critical to subsequently interpret cut point values and ultimately determine health risk status.
Although the WC measurement site suggested by major health organizations differs, there currently is only one set of values widely used as cut points for health risk classification. These were established in 1995 by Lean et al. (16) in Glasgow, Scotland, while measuring WC at the midpoint between the lowest rib and iliac crest. They determined that a man should not gain more weight if WC > 94 cm and a woman should not gain more if WC > 80 cm (i.e., “increased” risk). A man should lose weight with a WC > 102 cm and WC > 88 cm for a woman (i.e., “high” risk). These cut points for WC were based on BMI, with BMI > 25 kg/m2 considered “increased” health risk, whereas a BMI > 30 kg/m2 is indicated as a “high” health risk category. Lean et al. (16) used only BMI and did not consider VAT or other cardiometabolic risk factors (e.g., hypertension, high cholesterol) when establishing the WC cut points. Even though using BMI alone provides a fallible indicator of overall cardiometabolic risk, the WC cut points determined by Lean etal. (16) were widely adopted by major health organizations. NHLBI (1) suggests measuring WC superior to the iliac crest but uses cut points of Lean et al. (16) developed for measurement between the lowest rib and the iliac crest. Using cut points this way can lead to misclassification of health risk (28).
In a study comparing WC measurement sites, while using metabolic screening and CT scans, it was demonstrated that 54% more men and 68% more women were at risk for cardiometabolic disease using the umbilicus compared with the minimal waist measurement (29). In other words, a lot more people are classified as “at risk” when WC is measured at the umbilicus. Recognizing this, several researchers proposed new cut points based on measurement site (18) and BMI (2). Ethnicity (4) and age (23) also have been considered in the development of cut points because they may affect fat deposition patterns. For example, African Americans tend to have less VAT deposition, whereas Asians tend to have more, than whites with the same WC (4,19,24). We also know that, with age, abdominal fat mass typically increases, leading to different meanings for the same WC in a 25- versus 75-year-old (9). New cut points are being developed to address site and population specifics (Table 2), but it should be noted that none of these values are widely adopted.
TABLE 2: Suggested W...Image Tools
In a further attempt to determine how measurement site affects cardiometabolic risk classification, Caitlin Mason, Ph.D., and Peter T. Katzmarzyk, Ph.D., compared WC across four anatomic sites on 520 people (19). They took the WC at the umbilicus, midpoint between the lowest rib and the iliac crest, superior to the iliac crest, and at the minimal waist. Risk factors examined were resting blood pressure, fasting total cholesterol, high-density lipoprotein cholesterol, triglycerides, and glucose. They defined elevated cardiometabolic risk as two or more risk factors. Sensitivity and specificity of each WC measurement site were examined using the cut points developed by Lean et al. (16). Note that sensitivity is a measure of a test’s ability (e.g., WC) to predict the presence of a condition (e.g., metabolic syndrome), whereas specificity is the test’s ability to predict the absence of the condition. Mason and Katzmarzyk (19) reported that the measurement site chosen significantly affected prediction of cardiometabolic risk. In another study, they also reported (18) that the various WC measurement sites led to classification of high health risk caused by abdominal obesity (>102 cm) in as few as 23% (minimal waist) or as many as 34% (umbilicus) of 223 men studied. Site choice led to more dramatic differences in the women studied. Of 319 women, 31% were classified with a high health risk caused by abdominal obesity (>88 cm) using the minimal waist, but 55% were classified with a high health risk caused by abdominal obesity when umbilicus was the site (18). These findings highlight the importance of having a single accepted WC measurement site because disease risk prediction will vary depending on the site chosen.
WHICH IS THE BEST SITE?
There is currently no consensus on the best site for WC measurement, but emerging information is promising. New research suggests that measuring WC below the lowest rib may be best for identifying cardiometabolic disease risk based on VAT deposition patterns (24,29). The “lowest rib” site is the most anatomically superior WC site (i.e., anatomically located above minimal waist, umbilicus, and other recommended WC measurement sites), and more metabolically active VAT is found in the upper than lower abdomen (6,15). The suggestion to use a more superiorly located abdominal site for WC measurement is further strengthened by CT imaging studies of VAT at L1 to L2 (15) and at L2 to L3 of the lumbar spine (5,8). In contrast, the site just above the iliac crest has been shown to have the greatest correlation with total percent body fat, but this is not proven to be predictive of cardiometabolic risk (28). Ironically, an expert panel of the AHA recently recommended in a consensus statement that the iliac crest is the preferred WC measurement site (4).
In an effort to determine the best measurement site, Bosy-Westphal et al. (3) compared WC measures below the lowest rib, above the iliac crest, and midway between the lowest rib and the iliac crest. They examined 528 people and also followed 75 participants after dietary intervention for weight loss. MRI was used to determine VAT and SAT volumes, and metabolic risk factors (e.g., blood pressure, lipids, glucose) also were screened. This study allowed comparison of cardiometabolic risk, SAT, and VAT volume for each WC measurement site. Measuring WC below the lowest rib was the only site able to predict weight loss associated with decreased VAT in women. WC measurements at the iliac crest had a very low association with cardiometabolic risk factors and VAT in women. On the other hand, the site below the lowest rib had a strong correlation (r = 0.70 in women, r = 0.74 in men) with total VAT and cardiometabolic risk. The lowest rib is a fixed landmark (unlike the umbilicus) that will not move if body composition changes, and it is easily identified by a clinician. In summary, there is good logical and scientific reason to consider the site below the lowest rib the preferred WC measurement site.
IS WC A USEFUL CLINICAL MEASUREMENT?
Despite complications, research generally agrees that WC is avaluable clinical measure. WC appears to be a better indicator of cardiometabolic risk than solely using BMI (12,13,27) or WHR (22,23). However, when used in conjunction with BMI, WC measurements can effectively identify cardiometabolic disease risk within a BMI (kg/m2) category, particularly for those of a normal weight (22). In fact, ACSM (1) in its book ACSM’s Guidelines for Exercise Testing and Prescription (GETP) (see Table 4.1 in reference 1) encourages the use of WC together with BMI to determine disease risk. As an example, this table in the GETP (1) classifies a woman with a BMI of 30 to 34.9 as “high” risk if her WC is less than 88 cm but “very high” risk if her WC is more than 88 cm. Therefore, combining use of WC and BMI is valuable; however, the simple measurement of WC alone remains an effective means to identify risk for cardiometabolic disease.
Beyond identifying cardiometabolic risk, WC also is a low-cost measure that can be used to assess the effects of an intervention (e.g., altering diet or exercise habits). As Després et al. (6) noted, “weight loss… has been reported to induce a substantial mobilization of abdominal and visceral adipose tissue among high-risk abdominally obese patients.” BMI (or WHR) may not account for body composition changes that would lessen the risk of cardiometabolic disease in a client who has lost weight (12). WC, when consistently measured, may allow identification of risk-related changes that may otherwise only be seen using specialized imaging equipment or metabolic screening. WC changes are proven to be positively related to diet or exercise-induced reductions in VAT (26), and an NHLBI expert panel recommended WC measurement be used to follow changes in adiposity with weight loss (20). In conclusion, WC is a simple measure that is a potentially important predictor of abdominal obesity and cardiometabolic risk.
HOW DO WE USE WC MEASUREMENTS IN PRACTICE?
WC measurements are best used for repeated comparisons on a given client to assess if interventions such as exercise programming (or nutritional counseling) are effective at impacting VAT and related cardiometabolic risk. Using WC in your facility requires choosing a single measurement process. Train and ascertain that all professional staff consistently can apply this measurement through careful practice and evaluation. At this point in time, we recommend measuring WC below the lowest rib because the research described above (3,15,24,29) leads us to believe that it is the most clinically relevant measurement site. In your facility, however, you may choose to apply the ASM-recommended minimal waist or the ACSM recommended superior to the iliac crest as used in the large-scale national (i.e., NHANES III) survey that found this site to be effective at predicting metabolic risk. In any case, WC measured at a single site, and applied with careful/consistent measurement technique, should provide valuable information for your clients. Understand that choosing a measurement site for your facility can make your assessments less (e.g., minimal waist) or more (e.g., umbilicus) conservative, leading to less or more obesity classifications, respectively. Clinicians are urged to vigilantly watch for changing standards. For example, we might see major international organizations agree on measuring WC at a single site (maybe below the lowest rib) in the near future. However, there are currently no cut points specifically designated for the “lowest rib” site. For now, we recommend using Lean etal. (16) values as cut points for all WC sites because these values are the only standards widely accepted. Future research should be directed at developing acceptable cut points across ethnicities, age, and gender for WC measurement sites.
It helps us, as clinicians, to understand the prevailing limitations of the health assessments we use. Despite shortcomings (as seen with most health assessments), WC is a simple, affordable, and practical clinical tool that should be widely used. Hopefully, standardized protocols for WC measurement and appropriate cut points will be adopted by major organizations and be available for our clinical use in the near future. Until then, judiciously apply the valuable measure of WC for the benefit of your clients.
CONDENSED VERSION AND BOTTOM LINE
Waist circumference (WC) measurement is widely recognized as a screening tool for cardiometabolic risk. It is a better indicator of visceral adipose tissue (VAT) and metabolic risk than body mass index or waist-to-hip ratio. Despite this, major health organizations have not come to a consensus on an appropriate WC measurement site or values for risk cut points. WC measured below the lowest rib may be the best indicator of VAT and health risk compared with other measurement sites. Future research efforts should focus on standardizing a measurement protocol and developing appropriate and accepted values for cut points. In the meantime, we can still carefully use WC as a clinical tool and estimate of cardiometabolic risk. Clinicians can determine effectively if an intervention (e.g., an exercise or weight loss program) is having an impact on WC (and cardiometabolic risk) by establishing a consistent measurement protocol for use in their facility.
1. American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription. 9th ed. Baltimore (MD): Lippincot Williams and Wilkins; 2013.
2. Ardern CI, Janssen I, Ross R, Katzmarzyk PT. Development of health-related waist circumference thresholds within BMI categories. Obes Res. 2004; 12 (7): 1094–1103.
3. Bosy-Westphal A, Booke CA, Bocker T, Kossel E, et al. Measurement site for waist circumference affects its accuracy as an index of visceral and abdominal subcutaneous fat in a Caucasian population. J Nutr. 2010; 140 (5): 954–61.
4. Cornier MA, Després JP, Davis N, et al. Assessing adiposity: A scientific statement from the American Heart Association. Circulation. 2011; 124: 1996–2019.
5. Demerath EW, Reed D, Rogers N, et al. Visceral adiposity and its anatomical distribution as predictors of the metabolic syndrome and cardiometabolic risk factor levels. Am J Clin Nutr. 2008; 88: 1263–71.
6. Després JP, Lemieux I. Abdominal obesity and metabolic syndrome. Nature. 2006; 444 (14): 881–7.
7. Executive Summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III). JAMA. 2001; 585 (19): 2486–509.
8. Han TS, McNeill G, Seidell JC, Lean MEJ. Predicting intra-abdominal fatness from anthropometric measures: the influence of stature. Int J Obes. 1997; 21: 587–93.
9. Harris TB, Visser M, Everhart J, et al. Waist circumference and sagittal diameter reflect total body fat better than visceral fat in older men and women: The health, aging and body composition study. Ann NY Acad Sci. 2000; 904 (1): 462–73.
10. Housh TJ, Johnson GO, Thorland WG, et al. Validity and intertester error of anthropometric estimations of body density. J Sports Med Phys Fit. 1989; 29 (2): 149–56.
11. IDF. The IDF consensus worldwide definition of metabolic syndrome. Int Diabetes Fed. 2006;
12. Janiszewski PM, Janssen I, Ross R. Does waist circumference predicts diabetes and cardiovascular disease beyond commonly evaluated cardiometabolic risk factors? Diabetes Care. 2007; 30 (12): 3105–9.
13. Klein S, Allison DB, Heymsfield SB, et al. Waist circumference and cardiometabolic risk: A consensus statement from Shaping America’s Health: Association for Weight Management and Obesity Prevention; NAASO, The Obesity Society; the American Society for Nutrition; and the American Diabetes Association. Diabetes Care. 2007; 30 (6): 1647–52.
14. Klipstein-Grobusch K, Georg T, Boeing H. Interviewer variability in anthropometric measurements and estimates of body composition. Int J Epidemiol. 1997; 26 (1): S174–80.
15. Kuk JL, Blair SN, Church TS, Ross R. Does measurement site for visceral and abdominal subcutaneous adipose tissue alter associations with the metabolic syndrome? Diabetes Care. 2006; 29 (3): 679–84.
16. Lean MEJ, Han TS, Morrison CE. Waist circumference as a measure for indicating need for weight management. BMJ. 1995; 311: 158–61.
17. Lohman TJ, Roche AF, Martorell R. Anthropometric Standardization Reference Manual. Champaign (IL): Braun-Bloomfield; 1988: 28–80.
18. Mason C, Katzmarzyk PT. Variability in waist circumference measurements according to anatomic measurement site. Obesity. 2009; 17 (9): 1789–94.
19. Mason C, Katzmarzyk PT. Waist circumference thresholds for the prediction of cardiometabolic risk: Is measurement site important? Eur J Clin Nutr. 2010; 64: 862–7.
20. NHLBI. Clinical guidelines on the identification, evauluation, and treatment of overweight and obesity in adults. NIH. 1998; 98-4083: 16–7.
21. NIH. The practical guide to identification, evaluation, and treatment of overweight and obesity in adults. NIH. 2000.
22. Nordhamn K, Sodergren E, Olsson E, Karlstrom B, Vessby B, Berglund L. Reliability of anthropometric measurements in overweight and lean subjects: consequences for correlations between anthropometric and other variables. Int J Obes. 2000; 24: 652–7.
23. Onat A, Avci GS, Barlan MM, Uyarel H, Uzunlar B, Sansoy V. Measures of abdominal obesity assessed for visceral adiposity and relation to coronary risk. Int J Obes. 2004; 28: 1018–25.
24. Valsamakis G, Chetty R, Anwart A, Banerjee AK, Barnett A, Kumar S. Association of simple anthropometric measures of obesity with visceral fat and the metabolic syndrome in male Caucasian and Indo-Asian subjects. Diabetic Med. 2004; 21: 1339–45.
25. Ross R, Berentzen T, Bradshaw AJ, et al. Does the relationship between waist circumference, morbidity and mortality depend on measurement protocol for waist circumference? CMR. 2008; 1 (2): 20–2.
26. Ross R, Rissanen J, Hudson R. Sensitivity associated with the identification of visceral adipose tissue levels using waist circumference in men and women: Effects of weight loss. Int J Obes Relat Metab Disord. 1996; 20 (6): 533–8.
27. Schreiner PJ, Terry JJ, Evans GW, Hinson WH, Crouse III JR, Heiss G. Sex-specific associations of magnetic resonance imaging-derived intra-abdominal and subcutaneous fat areas with conventional anthropometric indices: The atherosclerosis risk in communities study. Am J Epidemiol. 1996; 144 (4): 335–45.
28. Wang J, Thornton JC, Bari S, et al. Comparison of waist circumferences measured at 4 sites. Am J Clin Nutr. 2003; 77: 379–84.
29. Willis LH, Slentz CA, Houmard JA, et al. Minimal versus umbilical waist circumference measures as indicators of cardiovascular disease risk. Obesity. 2007; 15 (3): 753–9.
© 2013 American College of Sports Medicine.