Most recent update: Tuesday, February 25, 2020 - 11:20

Bariatric News - Cookies & privacy policy

You are here

Waist circumference and obesity

Waist circumference and BMI should be routinely measured

they recommend that prospective studies using representative populations are carried out to address the need for BMI category-specific waist circumference thresholds across different ethnicities

Healthcare professionals should routinely measure waist circumference alongside BMI to properly assess and manage obesity-related health risk, according to a Consensus Statement from the International Atherosclerosis Society (IAS) and International Chair on Cardiometabolic Risk (ICCR), who state that decreases in waist circumference are a critically important treatment target for reducing potential health risks.

Decades of research have produced unequivocal evidence that waist circumference provides both independent and additive information to BMI for morbidity and mortality prediction, the authors state and they believe that on the basis of these observations, not including waist circumference measurement in routine clinical practice fails to provide an optimal approach for stratifying patients according to risk.

In 2017, the IAS and ICCR Working Group on Visceral Obesity convened in Prague, Czech Republic, to discuss the importance of abdominal obesity as a risk factor for premature atherosclerosis and CVD in adults (Supplementary Information) and agreed to work on the development of consensus documents which would reflect the position of the two organizations. This Consensus Statement, summarises the evidence that BMI alone is not sufficient to properly assess, evaluate or manage the cardiometabolic risk associated with increased adiposity and recommend that waist circumference be adopted as a routine measurement in clinical practice alongside BMI to classify obesity.

The statement, ‘Waist circumference as a vital sign in clinical practice: a Consensus Statement from the IAS and ICCR Working Group on Visceral Obesity’, published in the journal Nature, also identifies gaps in the knowledge, including the refinement of waist circumference threshold values for a given BMI category, to optimize obesity risk stratification across age, sex and ethnicity.

The authors report that:

  • Although the prevalence of obesity measured by BMI might have plateaued in some countries, the prevalence of abdominal obesity as measured by waist circumference is generally increasing.
  • The lack of inclusion of waist circumference in global obesity surveillance might inadequately characterise the health risk associated with the global obesity prevalence, as it seems that the prevalence of abdominal obesity is increasing.
  • Current obesity prevalence trends based on BMI alone should be interpreted with caution. We recommend that serious consideration should be given to the inclusion of waist circumference in obesity surveillance studies.
  • In categorical analyses, waist circumference is associated with health outcomes within all BMI categories independent of sex and age.
  • When BMI and waist circumference are considered as continuous variables in the same risk prediction model, waist circumference remains a positive predictor of risk of death, but BMI is unrelated or negatively related to this risk.
  • The strength of the association between waist circumference and morbidity and/or mortality is not fully realised until after adjustment for BMI.
  • The improved ability of waist circumference to predict health outcomes over BMI might be at least partially explained by the ability of waist circumference to identify adults with increased VAT mass.
  • The combination of BMI and waist circumference identifies a high-risk obesity phenotype better than either measure alone.
  • They recommend that waist circumference should be measured in clinical practice as it is a key driver of risk; for example, many patients have altered CVD risk factors because they have abdominal obesity.
  • Waist circumference is a critical factor that can be used to measure the reduction in CVD risk after the adoption of healthy behaviours.
  • Exercise and/or diet consistent with guideline recommendations are associated with substantial reductions in waist circumference, independent of age, sex or ethnicity.
  • Available evidence from RCTs suggests that exercise is associated with substantial reductions in waist circumference, independent of the quantity or intensity of exercise.
  • Exercise-induced or diet-induced reductions in waist circumference are observed with or without weight loss.
  • They recommend that practitioners routinely measure waist circumference as it provides them with a simple anthropometric measure to determine the efficacy of lifestyle-based strategies designed to reduce abdominal obesity.
  • Currently, no consensus exists on the optimal protocol for measurement of waist circumference and little scientific rationale is provided for any of the waist circumference protocols recommended by leading health authorities.
  • The waist circumference measurement protocol has no substantial influence on the association between waist circumference, all-cause mortality and CVD-related mortality, CVD and T2DM.
  • Absolute differences in waist circumference obtained by the two most often used protocols, iliac crest (NIH) and midpoint between the last rib and iliac crest (WHO), are generally small for adult men but are much larger for women.
  • The classification of abdominal obesity might differ depending on the waist circumference protocol.
  • They recommend that waist circumference measurements are obtained at the level of the iliac crest or the midpoint between the last rib and iliac crest. The protocol selected to measure waist circumference should be used consistently.
  • Self-measures of waist circumference can be obtained in a straightforward manner and are in good agreement with technician-measured values.
  • From the evidence available, they question the rationale behind current guidelines recommending that a single waist circumference threshold for white adults (men >102 cm; women >88 cm) be used to denote a high waist circumference, regardless of BMI category.

Finally, they recommend that prospective studies using representative populations are carried out to address the need for BMI category-specific waist circumference thresholds across different ethnicities. This recommendation does not, however, diminish the importance of measuring waist circumference to follow changes over time and, hence, the utility of strategies designed to reduce abdominal obesity and associated health risk.

“The main recommendation of this Consensus Statement is that waist circumference should be routinely measured in clinical practice, as it can provide additional information for guiding patient management…On the basis of these observations, not including waist circumference measurement in routine clinical practice fails to provide an optimal approach for stratifying patients according to risk,” the authors conclude. “..Numerous epidemiological studies and RCTs have now demonstrated that reductions in waist circumference can be achieved by routine, moderate-intensity exercise and/or diet changes…Health professionals should be trained to properly perform this simple measurement and should consider it as an important vital sign to assess and identify, as an important treatment target in clinical practice.”

To access this paper, please click here

Want more stories like this? Subscribe to Bariatric News!

Bariatric News
Keep up to date! Get the latest news in your inbox. NOTE: Bariatric News WILL NOT pass on your details to 3rd parties. However, you may receive ‘marketing emails’ sent by us on behalf of 3rd parties.