Waist circumference as a vital sign in clinical practice: a Consensus Statement from the IAS and ICCR Working Group on Visceral Obesity

Abstract

Despite decades of unequivocal evidence that waist circumference provides both independent and additive information to BMI for predicting morbidity and risk of death, this measurement is not routinely obtained in clinical practice. This Consensus Statement proposes that measurements of waist circumference afford practitioners with an important opportunity to improve the management and health of patients. We argue that BMI alone is not sufficient to properly assess or manage the cardiometabolic risk associated with increased adiposity in adults and provide a thorough review of the evidence that will empower health practitioners and professional societies to routinely include waist circumference in the evaluation and management of patients with overweight or obesity. We recommend that decreases in waist circumference are a critically important treatment target for reducing adverse health risks for both men and women. Moreover, we describe evidence that clinically relevant reductions in waist circumference can be achieved by routine, moderate-intensity exercise and/or dietary interventions. We identify 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. We recommend that health professionals are trained to properly perform this simple measurement and consider it as an important 'vital sign' in clinical practice.

Fig. 1. The prevalence of abdominal obesity and obesity measured in different studies.

Changes in the prevalence of abdominal obesity (measured using waist circumference) and general obesity (measured using BMI) measured in different studies during the time period indicated on the x axis. General obesity was defined as BMI ≥30 kg/m². Abdominal obesity was defined as waist circumference ≥88 cm and ≥102 cm for women and men, respectively. However, Xi et al. defined general obesity as BMI ≥28 kg/m² and abdominal obesity as waist circumference ≥80 cm and ≥85 cm for Chinese women and men, respectively. In addition, Barzin et al. defined general obesity as BMI ≥30 kg/m² and abdominal obesity as waist circumference ≥91 cm and ≥89 cm for Iranian women and men, respectively. Years given (for example, 1999–2011) indicate the years in which data were collected. F, female; M, male. Data are from refs^,–.

Fig. 2. Overview of potential role of functional and dysfunctional adipose tissue contributing to increased cardiometabolic risk.

The ability of subcutaneous adipose tissue (SAT) to expand through hyperplasia (generation of new fat cells) allows the safe storage of the excess energy from the diet into a properly expanding subcutaneous ‘metabolic sink’. When this process becomes saturated or in situations where adipose tissue has a limited ability to expand, there is a spillover of the excess energy, which must be stored in visceral adipose tissue as well as in normally lean organs such as the skeletal muscle, the liver, the pancreas and the heart, a process described as ectopic fat deposition. Visceral adiposity is associated with a hyperlipolytic state resistant to the effect of insulin along with an altered secretion of adipokines including inflammatory cytokines whereas a set of metabolic dysfunctions are specifically associated with increased skeletal muscle, liver, pancreas, and epicardial, pericardial and intra-myocardial fat. FFA, free fatty acid.

Fig. 3. Waist circumference is a modifiable risk factor that can indicate cardiometabolic risk, morbidity and mortality.

An illustration of the important role that decreases in waist circumference have for linking improvements in lifestyle behaviours with downstream reductions in the risk of morbidity and mortality. The benefits associated with reductions in waist circumference might be observed with or without a change in BMI.