Assessing
Adiposity: A Scientific Statement From the American Heart
Association
The following are 10 points to remember
about assessing adiposity.
1. There is a clear association between excess adiposity
and adverse health consequences, including cardiovascular
disease and diabetes. Reduction in adiposity is associated
with improvement in obesity-related comorbidities. Abdominal
obesity and general obesity are associated with cerebrovascular
disease (odds ratio [OR], 1.22-2.37), coronary heart disease
(OR, 1.21-3.25), and all-cause mortality (OR, 1.9-2.42).
2. The Centers for Disease Control and Prevention categories
of body mass index (BMI) are normal (18.5-24.9 kg/m2),
overweight (25-29.9 kg/m2), class I obesity (30-34.9 kg/m2),
class II obesity (35-39.9 kg/m2), and class III obesity
(>40 kg/m2). In the United States, 72.3% of men and
64.1% of women are overweight or obese. Among children,
16.9% are obese. Higher rates of obesity are observed among
non-Hispanic black and Hispanic women. Rates of obesity
are highest in the South, eastern Appalachia, and costal
North and South Carolina. Colorado has the lowest rate
of obesity.
3. BMI is not always the best measure to discriminate risk
of disease associated with adiposity. BMI has a pooled
sensitivity of 50% and a pooled specificity of 90% to identify
excess adiposity. Waist circumference is a simple method
to assess for central obesity, which has excellent correlation
with abdominal imaging. Sagittal abdominal diameter may
be a better marker of abdominal visceral adiposity than
waist-to-hip ratio, but has not been well validated.
4. Other measures include ratio of waist to hip. Computed
tomography (CT) scans can measure adiposity including visceral
adiposity accurately, but are not routinely used in clinical
practice. Imaging modalities including CT scans, magnetic
resonance imaging (MRI), and proton MR spectroscopy can
differentiate differences in liver fat content. Liver fat
content may be more related to diabetes mellitus and high
triglycerides than measures of visceral adiposity and,
thus, may identify individuals at greater risk for cardiovascular
disease and/or diabetes mellitus.
5. Visceral adiposity is associated with increased risk
of chronic diseases, including cardiovascular disease.
Factors associated with visceral adiposity include increasing
age, male sex, menopause, smoking, high caloric diets,
and sedentary behaviors. Blacks are more prone to subcutaneous
fats, whereas Asians are more prone to visceral fat deposits.
6. Assessing body composition can be done with several
methods. Anthropometric measures such as limb circumference
and skinfold thickness are low cost, but can underestimate
body fat. Near infrared interaction has been used to measure
body fat, but has been observed to have limited accuracy
compared to other measures. Additional measures include
hydrostatic weighing, plethysmography, dual-energy X-ray,
and absorptionmetry.
7. CT scans and MRI are now considered the gold standard
for measurement of fat distribution.
8. Measurement of ectopic fat or fat deposits in the liver,
skeletal muscle, and cardiac muscle is associated with
cardiometabolic risk factors. Proton MR spectroscopy can
reliably measure such ectopic fat deposits.
9. Changes in fat mass can be assessed through repeated
measures, including BMI and waist circumference. Changes
in waist circumference have been observed to correlate
with changes in cardiometabolic risk factors. To date,
no long-term studies have assessed the relationship of
changes in body fat composition and clinical outcomes.
10. Currently, BMI and waist circumference are the primary
tools to assess for adiposity. For all patients, counseling
regarding healthy dietary and activity behaviors is recommended.
Among patients with increased BMI or high waist circumference,
assessment of other cardiometabolic risk factors is recommended.
© 2011 by the American College
of Cardiology Foundation
The above message comes from "Cardiosource",
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