The Concept of CMR

Prevalence of obesity

In 1998, Flegal et al. (14) from the National Center for Health Statistics and Centers for Disease Control and Prevention (CDC) examined four different NHANES surveys (NHES I; 1960-62, NHANES I; 1971-74, NHANES II; 1976-80, and NHANES III; 1988-94). They reported a considerable increase in both overweight and obesity among adults in the United States. An 8.0% increase in obesity (BMI ≥ 30.0 kg/m²) was observed primarily between the NHANES II and III surveys (men and women 20 to 79 years of age, including all ethnic groups studied). The study also found that class III obesity prevalence (BMI ≥ 40.0 kg/m²) was over 10% among non-Hispanic black women in the middle age groups. In addition, the authors noted that the prevalence of non-obese overweight (BMI 25.0-29.9 kg/m²) was higher in men than in women, the prevalence of class I obesity (BMI 30.0-34.9 kg/m²) was similar in both genders, and more women than men had a  BMI ≥ 35.0 kg/m² (14).

Another study using data from NHANES surveys has suggested that obesity is associated with excess deaths in the United States (15). The strongest association between elevated body weight and mortality was observed in men and women 25 to 59 years of age who had a BMI ≥ 35 kg/m² and a relative risk of overall mortality of 1.83 (95% CI, 1.27-2.62) compared to the normal weight category. This study also highlighted that the association between excess body weight and mortality was stronger in NHANES I than in NHANES III, suggesting that public health and medical care improvements may be weakening the ties between elevated BMI and mortality. To illustrate the growing obesity epidemic, Figure 1 shows the increase in overweight and obesity rates in U.S. children and adults from 1960 to 2000.