Chapter Eight
Taking Control: Battling Obesity
through Exercise
It is imperative that women engage with the prevention of heart disease. One of the most important lifestyle changes that women can make is the initiation and continuation of an active lifestyle. Our society has become more sedentary over the last 20 years and overall health status has suffered. In general, obesity is thought to contribute to the development of heart disease through the production of an increasing number of individuals with hypertension, diabetes and hyperlipidemia. In fact, a study published in the New England Journal of Medicine in 1990 found that, in women, obesity was a strong predictor of coronary artery disease.1 In the study, women were divided into quartiles based on their weight and size, and researchers found that in women in the highest quartile for weight, there was a three-fold increase in fatal myocardial infarction and cardiovascular death, as compared to leaner women.1
Women who are obese may be more likely to develop metabolic syndrome, which has been associated with an increased risk of heart disease and stroke. According to the National Heart, Lung and Blood Institute, metabolic syndrome is defined as having at least three of the following risk factors: (1) large waistline (apple shape), (2) elevated triglycerides, (3) low HDL (high-density lipoprotein), (4) high blood pressure, (4) elevated fasting blood sugar or pre-diabetes, (5) proinflammatory state and (6) prothrombotic state.2 Elevated fasting blood sugar is an important component of metabolic syndrome and is associated with insulin resistance, which has been demonstrated to be a potent contributor to the development of heart disease.
Figure 8.1 The metabolic syndrome and heart disease.
Metabolic syndrome is becoming more commonplace among women as obesity levels rise. In fact, it is estimated that metabolic syndrome may eventually overtake smoking as a leading risk factor for heart disease, both in the US and abroad. It is critical that women recognize the symptoms of metabolic syndrome and intervene early to reduce their risk of heart disease and stroke. The individual components, as mentioned above, have been indentified as significant contributors to the development of heart disease. Abdominal obesity is most strongly associated with metabolic syndrome and is manifested as increase in waistline circumference. Lipid abnormalities are characterized by a very atherogenic combination of low HDL, high triglycerides and increased amounts of low-density lipoprotein particles.2 Hypertension has long been associated with vascular damage and stiffness of the arteries. Insulin resistance strongly correlates to cardiovascular disease risk and results in elevated serum glucose levels — which are strongly associated with the development of cardiovascular disease. Inflammation is a major contributor to heart disease and can be measured by elevations of C-reactive protein (CRP). Obesity has been shown to promote the release of inflammatory cytokines, which, in turn, result in higher levels of CRP.3 There is an increasing body of evidence that suggests that elevated CRP levels are associated with higher risk for heart disease.4 The final component, the prothrombotic state, occurs when there are higher levels of circulating clotting factors such as fibrinogen. Similar to CRP, these levels also rise with the elevation of cytokines in the bloodstream and may be interconnected. The elevation of clotting factors may contribute to the formation of plaques in the coronary arteries and promote the development of heart attacks in women with metabolic syndrome.5
Obesity is defined as a BMI of more than 30. BMI is calculated by taking the body weight in kilograms and dividing by the height in meters squared. This standard measure allows for standard comparison of multiple body types. Research has shown that BMI correlates quite well with an individual’s body fat composition.6 Interestingly, women tend to have more body fat at similar BMI levels as compared to men.7 Older adults tend to also have more body fat at similar BMI levels when compared to younger people.
The Centers for Disease Control (CDC) in the US has defined standard cutoff points for BMI for the purpose of defining levels of obesity, and these are based on recommendations for the World Health Organization. It is important to remember that these BMI standards are applicable only in those over 18 years of age — in children a different interpretation is utilized. Standard tables from the World Health Organization for BMI definitions are displayed in Table 8.1.
BMI has been shown to have a direct correlation with mortality in both men and women. In a recent publication, Adams et al. demonstrated that when compared to patients with normal BMIs, those with a BMI over 25 (and those that attained that BMI earlier in life) were found to have higher all-cause mortality.8 In fact, both weight gain and BMI at all ages were directly related to all-cause mortality. It is clear that obesity is a key component in the development of chronic disease. In women, obesity may be an even more significant risk factor for the development of coronary artery disease, particularly given the relationship of obesity to metabolic syndrome.
Table 8.1 The international classification of adult underweight, overweight and obesity according to BMI.
| BMI (kg/m2) | ||
| Classification | Principal cutoff points | Additional cutoff points |
| Underweight | <18.50 | <18.50 |
| Severe thinness | <16.00 | <16.00 |
| Moderate thinness | 16.00–16.99 | 16.00–16.99 |
| Mild thinness | 17.00–18.49 | 17.00–18.49 |
| Normal range | 18.50–24.99 | 18.50–22.99 23.050–24.99 |
| Overweight | ≥25.00 | ≥25.00 |
| Pre-obese | 25.00–29.99 | 25.00–27.49 27.50–29.99 |
| Obese | ≥30.00 | ≥30.00 |
| Obese class I | 30.00–34.99 | 30.00–32.49 32.50–34.99 |
| Obese class II | 35.00–39.99 | 35.00–37.49 37.50–39.99 |
| Obese class III | ≥40.00 | ≥40.00 |
Source: Adapted from WHO, 1995, WHO, 2000, and WHO, 2004.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
