A new consensus statement urges healthcare professionals to measure waist circumference in addition to body mass index in order to manage patients’ health and longevity and avoid obesity-related health risks.
The statement appears in the journal Nature Reviews Endocrinology. Robert Ross, who is a professor in the School of Kinesiology and Health Studies at Queen’s University in Ontario, Canada, is the first author of the paper.
In their statement, Prof. Ross and colleagues sum up the existing evidence that body mass index (BMI) is not enough to assess the cardiometabolic health risks of obesity on its own.
Their round-up of “decades of unequivocal evidence,” the authors hope, “will empower health practitioners and professional societies to routinely include waist circumference in the evaluation and management of patients with overweight or obesity.”
Why waist circumference is a ‘vital sign’
Studies that Prof. Ross and colleagues reference in their statement showed that waist circumference was the strongest predictor of visceral fat (the fat stored inside the abdominal cavity and around several vital organs), which poses the most significant health risk.
Secondly, they argue for the inclusion of waist circumference guidelines in the global obesity surveillance schemes, seeing that more and more people have abdominal obesity. Not having waist circumference guidelines alongside BMI may provide an inaccurate picture of the global prevalence of obesity and recent trends, they say.
Furthermore, the researchers explain, waist circumference is a strong predictor of death risk, unlike BMI. This may be partly because waist circumference helps identify people with large amounts of visceral fat. In conclusion, write Prof. Ross and colleagues:
“We recommend that measurements of waist circumference and BMI should become a standard part of clinical encounters (that is, an accepted ‘vital sign’).”
Lifestyle changes can affect waist size
Furthermore, “lifestyle-induced reductions in waist circumference are associated with improvements in cardiometabolic risk factors with or without corresponding weight loss,” write the authors, adding that waist circumference can be lowered with exercise or diet, “with or without corresponding weight loss.”
As a result, they recommend that doctors and health practitioners routinely monitor waist circumference to help determine whether lifestyle changes are working. Specifically, the statement continues, “We 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 open-access paper also includes a link to healthy waist guidelines and ways to measure one’s waist, as well as ethnicity-specific thresholds of what constitutes a healthy circumference.
Finally, the researchers question the current guidelines, “recommending that a single waist circumference threshold for white adults (men greater than 102 centimeters [cm]; women greater than 88 cm) be used to denote a high waist circumference, regardless of BMI category.”
Instead, Prof. Ross and colleagues recommend a lower threshold of:
- 80 cm for women and 90 cm for men of moderate weight
- 90 cm for women and 100 cm for men with overweight
- 105 cm for women and 110 cm for men with obesity I
- 115 cm for women and 125 cm for men with obesity II and III
“Individuals with measurements higher than these values have a high risk of future coronary events,” write the authors, and these thresholds indicate a higher health risk within each BMI category.
Still, the researchers admit that there are still knowledge gaps and “refinement of waist circumference threshold values for a given BMI category across different ages, by sex, and by ethnicity will require further investigation.”
“To address this need, we recommend […] prospective studies […] in the relevant populations,” they say. Prof. Ross and colleagues conclude:
“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.”
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