Obesity as Cardiovascular Risk Factor Introduction to Obesity and Worldwide Statistics
Obesity is a global epidemic affecting over 60% of the American population, who are classified as either overweight or obese. The medical costs attributed to obesity exceed $100 billion annually, making it a significant public health crisis. Despite the prominence of cardiovascular disease (CVD) and its risk factors in nursing research, the specific intersection of obesity and cardiovascular risk has been largely underexplored from a nursing perspective.
Nurses who have studied obesity and CVD risk factors typically include body weight measurements in their research, either directly or through self-reported data. These measurements are often analyzed using the Body Mass Index (BMI), calculated as weight/height (kg/m), to understand obesity’s impact on cardiovascular health.
Obesity in Children
Childhood obesity is a growing concern globally. In a study of 340 elementary school children, 53% had one or more risk factors for CVD, with 25% classified as obese. Among the obese children, 47% had additional risk factors for CVD (Cowell, Warren, & Montgomery, 1999). Furthermore, 84% of children with low fitness levels also had high blood pressure or were obese. Another study involving third-grade children identified high body fat percentages and environmental tobacco smoke exposure as the most prevalent risk factors for heart disease (Skybo & Ryan-Wenger, 2002).
These studies highlight that many children exhibit risk factors for CVD early in life, with some risk factors under their control, such as physical fitness and exposure to environmental tobacco smoke. Addressing childhood obesity is crucial for reducing long-term cardiovascular risk.
Obesity in Women
Obesity and its associated risk factors also differ by gender and socioeconomic status. A study of 1,945 women aged 23-53 years found that African American women of low and middle socioeconomic status (SES) were more likely to be obese, inactive, and smokers compared to their higher SES counterparts. For Caucasian women, only those with low SES had a high prevalence of these risk factors (Harrell & Gore, 1998). Even after controlling for income and education, African American women were more than twice as likely as Caucasian women to be obese and inactive.
Further analysis of the Canadian National Population Health Survey indicated an increase in obesity, diabetes, hypertension, and physical activity over time among women aged 20 and older (Wong & Wong, 2002). However, age, physical activity, hypertension, and household income—but not obesity—emerged as significant predictors of heart disease.
Obesity in Older Adults
Obesity poses significant cardiovascular risks in older adults. For example, in a study of patients following coronary artery bypass grafting (CABG), female sex (odds ratio 4.7) and obesity (odds ratio 3.7) significantly predicted hospital readmission (Sabourin & Funk, 1999). Another study of Korean-American elderly adults aged 60-89 years found that hypertension was the leading CVD risk factor, followed by high cholesterol, overweight, sedentary lifestyle, and smoking (Kim et al., 2001).
Intervention Studies
Nurses often appear as members of multidisciplinary teams in intervention studies that target obesity as a CVD risk factor. One such study examined cardiovascular fitness (VO₂ max) and physical activity rather than obesity per se as CVD risk factors in young adults (McMurray et al., 1998). The study found that those in the highest tertile of VO₂ max had a reduced risk of elevated cholesterol, blood pressure, and obesity. Following a 9-week exercise program for low-fitness young adults, only those who increased VO₂ max showed a reduction in risk for high cholesterol and systolic blood pressure.
Obesity and Post-Menopausal Women
Research has highlighted the specific cardiovascular risks associated with obesity in postmenopausal women. Nicklas and colleagues have focused extensively on obesity and sedentariness as major risk factors for CVD in this population and examined the effects of lifestyle modifications such as weight loss and physical activity. For example, a study examined the sequential effects of a 2-month American Heart Association (AHA) Step I diet followed by 6 months of a hypocaloric AHA diet and low-intensity walking in obese, postmenopausal women. The study found that:
- The AHA diet alone lowered concentrations of total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C).
- Weight loss increased HDL-C concentrations but did not significantly change total cholesterol or LDL-C levels in normocholesterolemic women.
- The AHA diet alone lowered HDL-C in the total sample, suggesting that a low-fat diet without substantial weight loss may not improve lipoprotein lipid risk factors for CVD in obese, postmenopausal women with normal lipid profiles (Nicklas et al., 1997).
Other studies examined racial differences in resting metabolic rate (RMR), fat oxidation, and VO₂ in obese postmenopausal women. Findings indicated that white women had significantly higher RMR, fat oxidation rates, and VO₂ than black women, even after adjusting for differences in lean mass (Nicklas et al., 1999).
High Cholesterol and Insulin Levels
The accumulation of visceral fat, independent of total body obesity, is widely associated with dyslipidemia, hypertension, glucose intolerance, and hyperinsulinemia in women. Research shows that reductions in visceral adipose tissue (VAT) are associated with improvements in VO₂ during a hypocaloric diet and exercise program (Lynch et al., 2001). Additionally, women in the lowest quintile for VAT had better lipid profiles and lower fasting glucose and insulin concentrations than those in higher VAT quintiles (Nicklas et al., 2003).
Weight Loss and Lipid Level
Studies in overweight and obese postmenopausal women suggest that weight loss can lead to reductions in adipose tissue lipoprotein lipase activity (AT-LPL), which is associated with improvements in lipid metabolic risk factors and decreased weight regain. Genetic studies also indicate that variations in the lipoprotein lipase gene and other genes may influence these outcomes, with certain variations associated with more problematic CVD risk factor profiles (Nicklas et al., 2003).
Obesity Etiology
Obesity is a complex condition influenced by a range of factors, including physiological, metabolic, genetic, cognitive, psychological, behavioral, environmental, social, and political factors. As a major risk factor for CVD—the leading cause of mortality in both women and men—obesity necessitates comprehensive research and intervention strategies.
Conclusion
Obesity is a critical public health issue that significantly contributes to cardiovascular risk across different populations, including children, women, and older adults. Nursing research has a vital role in addressing this intersection, particularly in developing and evaluating interventions that target obesity-related CVD risk factors. By understanding the etiology and impact of obesity, nursing professionals can contribute to effective prevention, management, and treatment strategies that improve patient outcomes and reduce the global burden of cardiovascular disease.