Weight loss and blood pressure control (Pro).

Overweight is an increasingly prevalent condition throughout the world. Current estimates, which are probably conservative, indicate that at least 500 000 000 people worldwide are overweight as defined by a body mass index (BMI) of between 25.0 and 29.9 and an additional 250 000 000 are obese with a BMI of 30.0 or higher.1 In the United States, recent data indicate that as much as 66% of the adult population is overweight or obese.2 Overweight and obesity are established risk factors for cardiovascular disease (CVD), stroke, noninsulin dependent diabetes (NIDDM), certain cancers, and numerous other disorders.3,4,5,6,7 It is also a risk factor for hypertension.8 Hypertension, defined as a systolic blood pressure in excess of 140 mm Hg or a diastolic blood pressure higher than 90 mm Hg, is also a globally increasing public health concern. Roughly 1 billion individuals worldwide are estimated to exhibit clinically significant elevated blood pressure with about 50 million of those residing in the United States.8 Hypertension, in turn, is associated with increased risk for CVD, stroke, renal disease, and all-cause mortality.9,10,11,12 The JNC VII report defines Stage 1 hypertension as blood pressure levels between 140 and 159 mm Hg systolic and 90 and 99 diastolic. Additionally, the report establishes a category of Prehypertension (Systolic blood pressure between 120 and 140 mm Hg or diastolic between 80 and 89 mm Hg). These 2 blood pressure classifications are deemed to be appropriate primary targets for lifestyle modification interventions, including weight loss. Higher levels of blood pressure, or stage 1 hypertension that is maintained over a long period, should be addressed primarily with medications or other physician directed treatments. There is a positive relationship between overweight or obesity and blood pressure and risk for hypertension. As early as the 1920s, a significant association between body weight and blood pressure was noted in men.13,14 In the intervening years, epidemiological studies have routinely confirmed this association. The Framingham Study found that hypertension is about twice as prevalent in the obese as the nonobese of both sexes.15 Stamler and colleagues16 noted an odds ratio for hypertension of obese relative to nonobese (BMI of less than 25) of 2.42 for younger adults and 1.54 for older ones. The Nurses Health Study17 compared women with BMIs of less than 22 with those above 29 and found a 2to 6-fold greater prevalence of hypertension among the obese. More recent data from the Framingham Study further support this relationship. Divided into BMI quintiles, Framingham participants of both sexes demonstrated increasing blood pressures with increased overweight. In this instance those in the highest BMI quintile exhibited 16 mm Hg higher systolic and 9 mm Hg higher diastolic blood pressures than those in the lowest quintile. For systolic blood pressure this translated into an increase of 4 mm Hg for each 4.5 kg of increased weight.18 In younger Canadian adults, Rabkin et al19 noted a 5-fold greater incidence of hypertension in individuals with BMIs of more than 30 relative to those less than 20 for both sexes. The public health burden of hypertension is certainly enormous. Although perhaps impossible to tease out because of associations with other risk factors, including overweight, hypertension is clearly a major contributor to most categories of chronic disease.20 Diseases of the heart and cerebrovascular diseases are the 1st and 3rd major causes of mortality in the United States accounting for more than 1/3 of all deaths annually.21 Hypertension is one of the clearest risk factors for both of these causes of death.8 Therefore, reduction in hypertension constitutes a major health goal for the immediate future. The federal government through the Healthy People 2010 initiative proposes to increase to 50% those in the adult hypertensive population with controlled hypertension.22 This contrasts with the currently estimated figure of 34%.8 Blood pressure control, the return of blood pressure to normotensive status, would have significant impact on mortality from heart and cerebrovascular diseases. In clinical trials antihypertensive therapy can result in reductions of incidence of stroke, myocardial infarction, and heart failure of between 20% and 50%.23 Ogden et al2 estimate that a 12-mm Hg decline in systolic blood pressure maintained over a period of 10 years in a population with initial stage 1 hypertension will reduce incident mortality by between 9%