Weight Loss and Blood Pressure Control (Pro)
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CONTROVERSIES IN
HYPERTENSION
Weight Loss and Blood Pressure Control (Pro)
David W. Harsha, George A. Bray
O verweight is an increasingly prevalent condition
throughout the world. Current estimates, which are
probably conservative, indicate that at least 500 000 000
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 2- to 6-fold greater
people worldwide are overweight as defined by a body mass prevalence of hypertension among the obese.
index (BMI) of between 25.0 and 29.9 and an additional More recent data from the Framingham Study further
250 000 000 are obese with a BMI of 30.0 or higher.1 In the support this relationship. Divided into BMI quintiles, Fra-
United States, recent data indicate that as much as 66% of the mingham participants of both sexes demonstrated increasing
adult population is overweight or obese.2 blood pressures with increased overweight. In this instance
Overweight and obesity are established risk factors for those in the highest BMI quintile exhibited 16 mm Hg higher
cardiovascular disease (CVD), stroke, noninsulin dependent systolic and 9 mm Hg higher diastolic blood pressures than
diabetes (NIDDM), certain cancers, and numerous other those in the lowest quintile. For systolic blood pressure this
disorders.3,4,5,6,7 It is also a risk factor for hypertension.8 translated into an increase of 4 mm Hg for each 4.5 kg of
Hypertension, defined as a systolic blood pressure in increased weight.18 In younger Canadian adults, Rabkin et
excess of 140 mm Hg or a diastolic blood pressure higher al19 noted a 5-fold greater incidence of hypertension in
than 90 mm Hg, is also a globally increasing public health individuals with BMIs of more than 30 relative to those less
concern. Roughly 1 billion individuals worldwide are esti- than 20 for both sexes.
mated to exhibit clinically significant elevated blood pressure The public health burden of hypertension is certainly
with about 50 million of those residing in the United States.8 enormous. Although perhaps impossible to tease out because
Hypertension, in turn, is associated with increased risk for of associations with other risk factors, including overweight,
CVD, stroke, renal disease, and all-cause mortality.9,10,11,12 hypertension is clearly a major contributor to most categories
The JNC VII report defines Stage 1 hypertension as blood of chronic disease.20 Diseases of the heart and cerebrovascu-
pressure levels between 140 and 159 mm Hg systolic and 90 lar diseases are the 1st and 3rd major causes of mortality in
and 99 diastolic. Additionally, the report establishes a cate- the United States accounting for more than 1/3 of all deaths
gory of Prehypertension (Systolic blood pressure between annually.21 Hypertension is one of the clearest risk factors for
120 and 140 mm Hg or diastolic between 80 and 89 mm Hg). both of these causes of death.8 Therefore, reduction in
These 2 blood pressure classifications are deemed to be hypertension constitutes a major health goal for the immedi-
appropriate primary targets for lifestyle modification inter- ate future. The federal government through the Healthy
ventions, including weight loss. Higher levels of blood People 2010 initiative proposes to increase to 50% those in
pressure, or stage 1 hypertension that is maintained over a the adult hypertensive population with controlled hyperten-
long period, should be addressed primarily with medications sion.22 This contrasts with the currently estimated figure of
or other physician directed treatments. 34%.8
There is a positive relationship between overweight or Blood pressure control, the return of blood pressure to
obesity and blood pressure and risk for hypertension. As early normotensive status, would have significant impact on mor-
as the 1920s, a significant association between body weight tality from heart and cerebrovascular diseases. In clinical
and blood pressure was noted in men.13,14 In the intervening trials antihypertensive therapy can result in reductions of
years, epidemiological studies have routinely confirmed this incidence of stroke, myocardial infarction, and heart failure
association. The Framingham Study found that hypertension of between 20% and 50%.23 Ogden et al2 estimate that a
is about twice as prevalent in the obese as the nonobese of 12-mm Hg decline in systolic blood pressure maintained over
both sexes.15 Stamler and colleagues16 noted an odds ratio for a period of 10 years in a population with initial stage 1
hypertension of obese relative to nonobese (BMI of less than hypertension will reduce incident mortality by between 9%
The opinions expressed in this editorial are not necessarily those of the editors or of the American Heart Association.
From the Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge.
Correspondence to David W. Harsha, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge,
LA 70808. E-mail david.harsha@pbrc.edu
(Hypertension. 2008;51:1420-1425).
© 2008 American Heart Association, Inc.
Hypertension is available at http://hyper.ahajournals.org DOI: 10.1161/HYPERTENSIONAHA.107.094011
1420Harsha and Bray Weight Loss and Blood Pressure Control: Pro 1421 and 11%. A population wide reduction of 5.5 mm Hg systolic of the rennin-aldosterone-angiotensin system, increased acti- or 3.0 mm Hg diastolic would result in an estimated 15% vation of sympathetic nervous system, and changes in natri- decline in incident coronary heart disease and a 27% decline uretic peptide. The wide range of potential mechanisms also in stroke.24,25 may be a major factor in accounting for the apparent The challenge, therefore, is how to accomplish this goal. heterogeneity in blood pressure response to any treatment. Numerous treatments have proved efficacious, at least in the Weight loss may variably and simultaneously impact one of short term, in clinically significantly reducing blood pressure more of these proposed routes of action. Because weight levels.8 Of these, weight loss offers a number of attractive status itself is a result of multiple causes, the fashion in which features. We will consider the evidence for weight loss it induces blood pressure change would not surprisingly be mediated reductions in blood pressure accomplished through variable. the more traditional means of caloric restriction and other Examination of these possible mechanisms raises one lifestyle modification strategies. We will not review the data important caveat about recommending weight loss for blood associated with weight loss resulting from pharmacological pressure control. This is the possibility that the effects of or surgical interventions except as it may relate to mainte- weight loss are mediated through some other system and that nance of weight loss. weight loss might not be an independent influence on blood Blood pressure alteration is theorized to be positively pressure status. associated with weight change. Although a number of studies Because most weight loss is accomplished through dietary have examined this from a perspective of weight loss and manipulation, it is possible that some aspects of diet, when reduction in blood pressure, there are little data in humans to altered, are the true determinants of blood pressure reduction. inform directly the idea that increase in weight relates to Chief among perceived dietary influences on blood pres- increased blood pressure at the individual level. Animal sure is sodium consumption. A large literature supports the studies have been the principle source of this information. notion that decreasing sodium consumption below that typi- Rocchini et al26 noted significant increases in blood pressure cal in Western society will result in a decline of blood accompanying weight gain from overfeeding in dogs. Hall et pressure. Numerous epidemiological studies have demon- al27 have confirmed this relationship. strated this relationship.34,35,36 Reductions in sodium intake On the other hand, numerous clinical interventions in on the order of 75 mmol/d or less have been associated with humans have examined the relationship of weight loss to a decline in blood pressure of about 1.9 mm Hg systolic and blood pressure change. Haynes28 reviewed 6 clinical trials 1.1 diastolic.36 The previously mentioned Trial of Hyperten- available to that time relating weight loss and blood pressure, sion Prevention found that a decrease of 44 mmol/d of noting that 3 of them showed a significant impact of weight sodium led to a 38% reduction in the incidence of hyperten- loss whereas the other 3 did not demonstrate a clear impact. sion in one of its treatment arms.30 The previously cited group More recently, a meta-analysis of 25 studies on this topic was analysis by Ebrahim and Smith32 found a pooled reduction of performed by Neter et al.29 The authors concluded that a 1-kg 2.9 and 2.1 mm Hg blood pressure level with varying degrees loss of body weight was associated with an approximate of sodium restriction. The Dietary Alterations to Stop Hyper- 1-mm Hg drop in blood pressure. Further this blood pressure tension Study (DASH-Na) found a maximum reduction of reduction was accomplished without the necessity of also about 6.7 mm Hg systolic and 3.5 diastolic in blood pressure attaining normal weight status. The Trial of Hypertension with an approximate 100-mmol/d reduction in sodium intake Prevention (TOHP), one of the largest of these studies, in those with elevated blood pressure on a typical American included a weight loss intervention arm.30 In this instance, a diet. An approximate 50 mmol/d reduction in sodium con- 2-kg loss in weight over a 6-month period resulted in a sumption led to a blood pressure decline of 2.1 and decline of 3.7 mm Hg in systolic and 2.7 mm Hg in diastolic 1.1 mm Hg systolic and diastolic.37 These findings were blood pressure. In addition, a 42% decline in the instance of produced in the absence of weight loss. hypertension was noted on this sample.31 The jury of scientific opinion is still out on the degree to Another analysis of multiple clinical trials of blood pres- which weight loss or sodium restriction make independent sure reduction was conducted by Ebrahim and Smith.32 In this contributions to blood pressure reduction. An early study, report, 8 trials were examined for the effects of weight loss on Dahl et al38 found sodium restriction in low calorie diets to be blood pressure and concluded that weight gain was associated the primary cause of blood pressure reduction. This is also the with increased blood pressure whereas weight loss resulted in finding of Fagerberg et al.39 Several more recent studies have reduced blood pressure. Blood pressure reductions were on sided with weight loss as having an independent effect on the order of 5.2 mm Hg both systolic and diastolic for varying blood pressure reduction. Reisen et al40 found blood pressure degrees of weight reduction. reductions on the order of 3 mm Hg for each kg of weight loss Given the established association between weight change in a sample of hypertensive men with no sodium restriction. and blood pressure status, the question arises as to how this Tuck et al41 and Maxwell et al42 additionally reported sodium interaction functions physiologically. Rocchini33 identifies independent effects of weight loss in a sample of hyperten- numerous potential biological mechanisms by which weight sive men as well. loss or fat loss might lead to parallel declines in blood Other dietary constituents have been implicated in the pressure. Among them are reductions in insulin resistance, control of blood pressure as well. Vegetarian diets are widely enhanced sodium retention, alterations in vascular structure associated with lower blood pressure levels.43 The Dietary and function, changes in ion transport, enhanced stimulation Approaches to Stop Hypertension Trial25 demonstrated that a
1422 Hypertension June 2008 diet high in fruit, vegetable, and low-fat dairy servings could interventions saw sustained weight loss and blood pressure reduce blood pressure by 5.3 and 3.0 mm Hg systolic and reduction. The active intervention without the DASH diet diastolic blood pressure, respectively, in the absence of either resulted in an average weight loss of 3.8 kg, that with the weight loss or sodium restriction. Raben et al44 found that DASH diet of 4.3 kg. Mean blood pressure reductions significantly increased sucrose consumption led to notewor- (systolic/diastolic) were 8.6/6.0 and 9.5/6.2 mm Hg for the thy increases in both weight and fat mass as well as increases same intervention arms, respectively. Urinary sodium reduc- in blood pressure on the order of 4 mm Hg. tions were 18.4 and 24.5 mmol/d, respectively, for each group Likewise, physical activity has been shown to influence as well. blood pressure levels and is additionally a part of the The Trial of Hypertension Prevention examined 181 par- recommended regimen of weight loss strategies.8 Bouchard et ticipants for weight loss or sodium reduction and blood al45 examined the pertinent studies to that time and concluded pressure for 7 years of follow-up.49 The sample was randomly that approximately 1 hour per day of low to moderate level assigned to a nontreated control, a sodium reduction, or a physical activity could support weight loss but that such a weight loss arm. The active component of the intervention program would require several years to be completely effec- lasted 18 months but individuals were further monitored for tive. Ebrahim and Smith32 studied 8 clinical trials in which blood pressure, weight, and dietary status for 7 years. Incident exercise was a primary component in blood pressure reduc- hypertension was the outcome variable of interest. The tion. They found modest impacts on blood pressure reduction weight loss group in the absence of sodium restriction, which of 0.8 to 3.7 and 0.2 to 1.0 mm Hg resulting from primarily had an average reduction of 5 kg in weight at 18 months,30 low levels of physical activity. A meta-analysis of the effects demonstrated an incidence of hypertension of 18.9% after 7 of physical activity on blood pressure conducted by Kelley et years. This contrasts with the sodium reduction in the absence al46 led the authors to predict a decline in systolic blood of weight loss group which found an incidence of hyperten- pressure of 3 to 5 mm Hg associated with moderate physical sion of 22.4% over the same period. These results were found activity. Whelton et al47 reported a meta-analysis of normo- in spite of the fact that much of the weight in the weight loss tensives with significant reductions in blood pressure atten- group had been regained at year 7. dant to a variety of types of physical activity. Interestingly, The Hypertension Prevention Trial followed 841 individ- although there appears to be consensus among these investi- uals for up to 3 years in caloric restriction/weight loss, gators that increased physical activity drives somewhat larger sodium reduction, caloric restriction and sodium reduction, declines in blood pressure, the nature of this relationship is and sodium reduction and increased potassium intervention unclear. Although there might be a dose response relationship arms.50 At 3 years of follow-up, the caloric restriction group in the largest sense, most of these studies examine the impact had maintained weight loss about 4% of baseline and dem- of low to moderate physical activity and therefore have a cap onstrated a 5.1/2.4-mm Hg reduction in blood pressure. The on the degree they are capable of examining the full impact of other dietary interventions resulted in smaller amounts of exercise on blood pressure. blood pressure reduction. The authors recommend caloric Because weight loss cannot be accomplished in the ab- restriction and accompanying weight loss as the strategy of sence of some combination of dietary or physical activity choice in influencing blood pressure. behaviors, separating independent effects of each component Most recently the Weight Loss Maintenance program has on blood pressure is extremely challenging. It is clear, released its findings.51 In this instance, 1083 participants who however, that weight loss, regardless of how obtained, is had previously lost 8.5 kg or more were enrolled in a associated with clinically significant reductions in blood self-directed control or 1 of 2 treatment arms for study of pressure. weight status over a 30-month period. Although all 3 groups Another issue is the extent to which maintained weight loss exhibited some regain over this time, all maintained at least continues to influence blood pressure status. The majority of about 3 kg of weight loss. One arm, a monthly personal studies linking weight loss to blood pressure reduction do so contact group, maintained a larger 4.5-kg weight loss. All only in the short term, usually examining impacts on a scale levels of maintained weight loss would result in significant of less than 1 year. The effect of longer term weight loss has reductions in blood pressure in the general population. predictably been much less examined. A number of clinical Several other smaller scale studies have documented a trials have examined the issue on the scale of more than 1 positive association between weight loss maintained for year. periods of up to 2 years and reduced blood pressure.52,53,54 In The Premier Trial followed 810 individuals with initial sum, it is clear that weight loss reduces blood pressure elevated blood pressure or stage 1 hypertension for 18 months reduction and that the blood pressure benefits are retained after randomization to control or either of 2 putatively heart over at least the short to midperiod, particularly in those who healthy active interventions.48 Both active interventions maintain the weight loss.31 counseled an increase in physical activity, and either a The effects over longer time frames are less clear. Sjostrom reduced fat and calorie diet, or a diet high in fruits, vegeta- et al55 report 8 years of follow-up on the relationship of bles, and low fat dairy servings using the DASH dietary weight loss to blood pressure in a group 1157 obese partici- model.25 Both active interventions also counseled reduction pants who received gastric bypass surgery to induce weight in sodium intake. Weight and blood pressure change were loss. Initial weight losses of 18% of presurgical body weight observed at baseline, at interim periods, and at the end of 18 were associated with a decline in blood pressure of about months of intervention. At the end of the trial both active 12 mm Hg systolic and 8 mm Hg diastolic. Over a 6- to
Harsha and Bray Weight Loss and Blood Pressure Control: Pro 1423 8-year period, weights increased only very slightly in this creases in blood pressure level. The result is a situation in group whereas blood pressure levels rebounded and, at the which it is not practicable to sort out independent causal end of the study, were similar to or higher than untreated effects. The argument then might emerge as to whether controls. The authors themselves, however, are skeptical that dietary or physical activity is a more desirable target for blood this is a generalizeable finding pointing to methodological pressure control. In these cases, however, data on recidivism and analytic inconsistencies in their sample.56 It remains for are not much more encouraging.62 Adoption of the entire other research examining maintained weight loss. package of lifestyle changes, appropriate eating, physical Taken in its totality, it is clear that weight loss is associated activity, and attention to weight management, yields the with a decline in blood pressure at least in the short and greatest likelihood of success.48,61 Overweight and obesity are midterm. These findings extend even to those initially in the best seen in this light as an ongoing major risk factor for normotensive range and hold for both genders and all ethnic hypertension, requiring life-long surveillance for both and groups examined. This conclusion is endorsed by the JNC VII immediate treatment as indicated by physician review. expert panel and has become a part of the suggested lifestyle And, at least in the case for blood pressure management, armamentarium in combating hypertension.8 Undoubtedly, the bar may not be so high as for overall success in weight much of the attractiveness of suggesting weight loss stems loss. Data clearly show that modest reductions in weight can from its multipurpose healthy nature. Not only is weight have an impact on blood pressure.20,29,63 Weight loss in the reduction associated with improved blood pressure control range of 2 to 4 kg are associated with systolic blood pressure but it confers benefits in the management of many other declines in the range of 3 to 8 mm Hg, a clinically significant disorders including Type II diabetes, musculo-skeletal disor- impact.30,31,32,48,49 Additionally, these impacts are felt rapidly ders, some cancers, and other health concerns including all as weight is lost usually within a few weeks48 and appear to cause mortality.3,4,5,6,7 me maintained, with corresponding maintenance of weight Nevertheless, using weight loss as sole means of accom- loss, for periods of at least 18 months to 3 years.49 Data on plishing blood pressure control is not without problems. Chief long term maintenance of weight loss are still to be produced. among these is the difficulty involved with achieving and Such studies are, clearly, both expensive and, by definition, maintaining optimal weight. Most who attempt weight loss time consuming. Emerging information from such programs achieve little in this regard, and most who are initially as the Weight Loss Maintenance study,51 however, yield successful rebound to their early status or higher.57,58,59 In the some confidence that, through appropriate treatment includ- grimmest scenarios, the net result is not only a population at ing lifestyle modification, weight can be lost and kept off. increased biomedical risk but also suffering from a number of Perhaps the largest problem with weight reduction as the psycho-social insults resulting from these failures.60 Never- primary mechanism for blood pressure control is that it is theless, weight loss is successfully accomplished and is ethically appropriate only for those with stage 1 hypertension maintained by a significant percentage of those who attempt or less. Clinical considerations require drug or other more using only lifestyle modifications.61 The methods and strate- intensive interventions in those with more elevated blood gies used are still developing and, if careful attention is paid pressures. Nevertheless, those in the prehypertensive and to refining them, the result will undoubtedly be improvement stage 1 hypertensive range constitute about 95 to 100 million in those achieving weight loss and a decline in recidivism.62 Americans, about 40% of the adult population.64 This demo- Maintenance of weight loss remains the challenge. Wing and graphic is a very large target for weight loss intervention, and Phelan61 report that approximately 20% of those attempting one that has the potential for considerable public health weight reduction via lifestyle modification are successful at impact. long term weight control. Research into the mechanisms by In conclusion, weight loss is clearly associated with a which these results are obtained should increase these success decrease in blood pressure as well as numerous other im- rates. It should be noted that the impact of weight loss on provements in biomedical status. Its accomplishment is done blood pressure does not require achievement of optimal successfully as the major component of a spectrum of weight (BMI ⬍25.0). Smaller decrements of weight loss appropriate lifestyle modifications. Strategies for achieving clearly are of clinical significance in controlling blood pres- long-term weight loss are emerging, and the proportion of sure levels. Likewise, complete maintenance of weight loss is those who are successful is growing. As a major public health not necessary in this regard. Some recidivism in weigh loss is issue, the management of overweight is of the highest priority normal but, as long as weight is still below baseline level, and is receiving major support from the federal government there can be impact on blood pressure.31 and other institutions. Successfully accomplishing national An additional issue, alluded to earlier, is the degree to goals for weight management can supply additional benefits which weight loss may be identified as an independent in the reduction of blood pressure and the associated biomed- influence on blood pressure status. As noted weight loss, at ical burden of risk for CVD and stroke. least via traditional approaches, can only be accomplished through some combination of diet and physical activity Sources of Funding changes. Numerous dietary components have been identified Supported by Lower Mississippi Delta Nutrition and Health Initia- as potentially impacting blood pressure, most notably sodium tive (USDA Grant No. 58-0101-5-018, Amendment 1). intake. But increased fruit and vegetable consumption is clearly pertinent as are numerous other macro and micronu- Disclosures trients.25 Physical activity, likewise, is associated with de- None.
1424 Hypertension June 2008
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Response to Weight Loss and Blood Pressure Control: The Pro Side
Allyn L. Mark
Harsha and Bray argue that diet and behavioral modification produce significant and sustained weight loss and that this
modest diet-induced weight loss diet is effective in treating mild hypertension. I remain unconvinced and deeply skeptical
on both points. I refer the reader to my companion article in this issue and to my recent article “Weight reduction for
treatment of obesity-associated hypertension: nuances and challenges” in Current Hypertension Reports (2007;9:368 –372).
Harsha and Bray highlight the recent Weight Loss Maintenance trial. I’m unimpressed. Like previous trials, it shows weight
regain with only modest residual weight loss. The duration of the trial was not long enough to establish sustained weight
loss, and there was no measurement of blood pressure. Further, there are questions about the pragmatism of long-term
widespread lifestyle modification in the “real world.” In addition, although even modest weight loss produces an early
reduction in blood pressure, the long-term reductions in blood pressure are much less impressive than the short term
reductions. One more nail in the coffin of the idea that weight loss is the answer to hypertension in obesity is the following.
In patients undergoing bariatric surgery for morbid obesity, although blood pressure decreases initially, it returns to control
levels after 6 to 8 years despite substantial and sustained decreases in body weight. In summary, chronic blood pressure
reduction during dieting and weight loss is not as sustained or pronounced as generally assumed.You can also read
