February 2022 Issue
Hypertension & Body Weight
By Carrie Dennett, MPH, RDN, CD
Vol. 24, No. 2, P. 20
An Overview of the New AHA Guidelines on Medical vs Lifestyle Weight Loss Strategies to Lower Blood Pressure
About 45% of adults in the United States have hypertension, which means they have systolic blood pressure at or above 130 mm Hg and diastolic blood pressure at or above 80 mm Hg, or are already taking antihypertensive medications.1 This is of course concerning, given that hypertension is a major risk factor for CVD, including myocardial infarction (heart attack), heart failure, and stroke, as well as chronic kidney disease and premature death.
In November 2021, the American Heart Association (AHA) released a scientific statement recommending that doctors focus less on prescribing lifestyle modifications (especially for weight loss) as a strategy for treating hypertension in patients with a BMI in the “obese” range—often referred to as “obesity hypertension”—and instead consider weight loss medications or metabolic/bariatric surgery.2
While this move recognizes that “eat less, move more” interventions are unlikely to result in sustained weight loss—for the majority of adults who attempt intentional weight loss, any losses are short term2,3—it still places an emphasis on weight loss for hypertension treatment and prevention, despite research demonstrating that diet and lifestyle can reduce blood pressure independent of weight loss. Today’s Dietitian unpacks this study.
So how does “obesity hypertension” differ from “regular” primary hypertension, other than body size?
Because having a BMI in the “obese” range often co-occurs with—and is considered to be a major risk factor for—hypertension, weight loss is commonly recommended as a treatment strategy. However, it’s increased levels of visceral fat, not subcutaneous fat, that has a strong association with new cases of hypertension, and people with a lower BMI can have high levels of visceral fat, a phenomenon known as “normal weight obesity.”2
“Obesity hypertension seems to be regular hypertension with a serving of fatphobia,” says Fiona Willer, PhD, AdvAPD, an advanced accredited practicing dietitian and nutrition lecturer at Queensland Institute of Technology in Australia. “All of these separate processes that they’re blaming on the weight should and could actually be targets of concern, but it’s perceived as simpler to go after what they see as the most obvious ‘issue.’”
Both hypertension and having a BMI in the “obese” range are associated with damage to blood vessels and the heart, kidneys, and brain. However, the authors of the AHA statement wrote, “The relationship between obesity and risk of target organ damage dissipates after adjustment for hypertension, suggesting that hypertension is a key explanatory factor for target organ damage in obesity.”2
“This is a really interesting point,” Willer says. “They suspect that hypertension may be the driver of organ damage, as it is in smaller bodies. We have effective medications to reasonably mitigate this risk. Taking the position that larger-bodied people should be denied medication while they starve themselves [through calorie restriction] is discriminatory. Also, weight loss does not affect kidney function—a damaged kidney does not miraculously repair with weight loss.”
Willer says that because weight loss through calorie restriction has such an immediate blood pressure–lowering effect, “when it is compared with blood pressure medication in the short-medium term, it looks superior, but it is metabolic cosplay, a temporary illusion that is, by definition, unsustainable.”
Weight-Neutral Hypertension Interventions
Many types of interventions have been shown to successfully lower blood pressure, at least in the short term. The 2017 guidelines from the AHA, American College of Cardiology, and related professional organizations recommend blood pressure–lowering medications for primary prevention of atherosclerotic cardiovascular disease in adults at elevated risk who also have hypertension. The guidelines also recommend several nonpharmacological interventions, including the DASH (Dietary Approaches to Stop Hypertension) diet, sodium reduction, potassium supplementation, increased physical activity, and reduction in alcohol consumption for preventing hypertension in adults with elevated blood pressure and for those managing mild hypertension.4
Here’s a look at what some of the research says about the impact physical activity and diet have on lowering hypertension.
• Physical activity. “Exercise is very much a piece of the puzzle, as it directly improves blood pressure,” says Tracy Severson, RD, LD, a dietitian at the Center for Preventive Cardiology at the Oregon Health Sciences University Knight Cardiovascular Institute in Portland. A 2018 review of physical activity intervention studies among postmenopausal women with hypertension found that aerobic exercise in particular lowers blood pressure via multiple different biological pathways, even when there was no significant weight loss.5 Unfortunately, people in larger bodies regularly experience weight-related stigma and discrimination in physical activity settings. In fact, research has found they often cope with such experiences by simply removing themselves from these settings to feel safe.6
• Dietary patterns. Both the 2021 AHA statement and the earlier 2017 guidelines emphasize that while many diets have been shown to lower blood pressure, most notably the Mediterranean diet, the DASH eating plan is the diet best demonstrated to be effective for lowering blood pressure.2,4 Because the DASH diet is high in fruits, vegetables, and low-fat dairy products, it increases intake of potassium, calcium, magnesium, and fiber, all of which have positive effects on blood pressure. While most of the DASH clinical trial evidence comes from short-term feeding studies, lifestyle changes involving a DASH diet intervention have been successful in at least two trials that had fouror six-month follow-ups.4
Severson says her patients see the most improvement in their blood pressure when they focus on reducing intake of highly processed foods and restaurant meals. “Most people with hypertension know they should cut back on salt, but that usually means they stop picking up the salt shaker, which only accounts for about 11% of the sodium in American diets,” she says. “By making basic changes like cooking at home and replacing highly processed foods with fruits and vegetables, not only will they reduce sodium intake, they will also increase important nutrients for blood pressure management, such as potassium and magnesium.”
Because she finds that individualized goals are more effective and sustainable, Severson rarely mentions the DASH or Mediterranean diets by name, though both are effective at lowering blood pressure. “I definitely work the elements of the DASH diet into my education with patients, but I find that even healthy plans such as these tend to trigger a diet mentality when they are recommended, which all too often leads to the patient one day being ‘off’ the diet. Like most RDs, I’m much more interested in smaller changes that we can build on over time,” she says.
Patients may do everything right, Severson says, and still have uncontrolled hypertension. “It’s important to remind them that, without their healthful diet and lifestyle, their blood pressure would be even higher, and they would potentially require even more medication,” she says. “A healthful lifestyle is always beneficial, not only for blood pressure but for other cardiovascular risk factors as well, even if it isn’t sufficient to achieve blood pressure goals.”
• Pharmacotherapy. Results from the Systolic Blood Pressure Intervention Trial (SPRINT) published in 2019 found that BMI doesn’t appear to modify the risks and benefits of intensive blood pressure lowering (ie, reducing systolic blood pressure to 120 mm Hg rather than the standard 140 mm Hg). BMI wasn’t significantly associated with new incidence of cardiovascular cases or with adverse drug effects. The authors concluded that intensive blood pressure lowering “may represent an important cardiovascular risk reduction strategy among people with BMIs in the ‘obese’ range.”7
“It should always make sense to try the least invasive and burdensome course of action first,” Willer says. “The [SPRINT study] clearly shows that intensive pharmacotherapy is effective across the BMI span, and that a BMI of 30 is associated with more favorable outcomes. Continuing to position a BMI of 18.5 to 25 as a primary goal isn’t supported by current best evidence.”
Weight Loss Pharmacotherapy
Despite non–weight loss options, the 2017 AHA guidelines state that while achieving “ideal weight” may be optimal, weight loss of at least 1 kg (2.2 lbs) for patients with BMIs above 25 kg/m2 through lifestyle, weight loss medications, or surgery is recommended.4 In the 2021 AHA statement, the authors argue that weight loss, dietary changes, and physical activity increases are difficult to maintain—warranting stronger consideration of “antiobesity” drugs and metabolic/bariatric surgery.2
“The paper notes that there’s significant recidivism of lifestyle interventions,” Willer says. “My research—and Health at Every Size® trials—has shown that when weight loss is the expected and celebrated outcome, changes to dietary patterns aren’t maintained when weight regain occurs. More research on outcomes experienced when weight loss is not the goal is needed desperately.”
Based on long-term weight loss studies, Severson says it’s possible to maintain 5% weight loss over time, but that for many people, this amount of weight loss wouldn’t feel like a success, even if it yields improvements in blood pressure and other health markers. “Focusing on health-promoting behaviors and making positive, sustainable changes to one’s diet can feel much more rewarding than the rather soul-crushing diet/regain cycle,” she notes.
Severson adds that when having a discussion with patients about weight loss and realistic goals, it’s a disservice to them not to discuss weight loss medications and bariatric surgery. “These are evidence-based treatments for a chronic disease, and they should be discussed as viable options,” she says. “Health care providers are generally quite comfortable prescribing a blood pressure–lowering medication for hypertension or a statin for hyperlipidemia, but few consider the utility of prescribing a weight loss medication, which would potentially improve both blood pressure and lipids along with promoting weight loss— more ‘bang for your buck,’ so to speak, in terms of pill burden and potential side effects.”
But if diet, physical activity, and antihypertensive medications can be effective as recommended primary treatments for hypertension, is it extreme to use surgery to treat hypertension in patients with a BMI in the “obese” range? This is an especially pertinent question given that the AHA acknowledges in its 2021 scientific statement that more randomized controlled trials are needed to assess the effects of metabolic/bariatric surgery on downstream risk reduction of the more serious endpoints of chronic kidney disease, stroke, and heart failure.2 Because the surgery has been shown to lower blood pressure immediately—even before weight loss starts—via mechanisms that are still unclear, it’s understandable why this can be an appealing option for some.
“While patients are still in the hospital, we stop any diuretics they are on for hypertension, and we also discharge them with 50% less hypertension medication,” says Melissa Majumdar, MS, RD, CSOWM, LDN, metabolic and bariatric coordinator at Emory University Hospital Midtown in Atlanta, and an Academy of Nutrition and Dietetics media spokesperson. “About half to two-thirds of patients will have resolution of hypertension long term. We know that, and we account for that so we don’t have hypotension.”
Anyone reading the 2021 AHA statement who isn’t familia with metabolic/bariatric surgery might think that the surgery is a simple one-stop method of treating hypertension—but it’s not. “My hope for anyone reading this is that they realize this is a layered approach, but that may not be the case if doctors aren’t familiar with metabolic surgery,” Majumdar says.
That layered approach includes dietary and physical activity interventions that begin long before the surgery and continue well afterward, she says. Presurgery, patients take nutrition classes and meet with a dietitian and other members of the multidisciplinary team, which includes psychologists or other licensed behavioral health care providers.8 There are also postsurgical nutrition follow-ups.
The in-hospital morbidity and mortality rates for metabolic surgery are 9% and 0.1%, respectively, with complication rates of 10% to 17% and a 30-day mortality rate of 0.08%.2 But this isn’t a complete picture of potential complications from metabolic surgery.
“There is a real problem with the reporting of weight loss surgery complications in that only short-term complications tend to be discussed,” Willer says. “Bariatric surgery—with its effort, the lifelong nutritional vulnerability, and the financial cost that comes with it—is a heavy price to pay for not having to take as much blood pressure medication.”
While metabolic/bariatric surgery is safer than it has ever been, it does pose risks that go unmentioned in many research studies, which focus on factors such as infection and readmission rate rather than psychosocial health.9 For example, while many patients report reduction in depressive symptoms post metabolic surgery, a subgroup of those patients experience a recurrence of depression in the long term, and some patients suffer from new onset of depression.10 A 2019 meta-analysis found that post– bariatric surgery patients had higher self-harm/suicide attempt risk compared with age-, sex-, and BMI-matched controls.11
An increase in alcohol use disorders also has been observed in postbariatric patients, and the term “addiction transfer” often is used to describe trading compulsive eating for process addictions, such as gambling or shopping, or substance addictions. However, Majumdar says that research doesn’t support the validity of the term “addiction transfer,” citing a 2019 review article that concluded that anatomical changes and alterations in how alcohol is metabolized may contribute to new cases of alcohol use disorder.12
While surgery is more likely to result in lasting weight loss than diet and lifestyle interventions, some individuals never obtain satisfactory weight loss (primary nonresponders), or they regain weight over the long term (secondary nonresponders). There are several reasons why this may occur, including the type of surgery. Roux-en-Y gastric bypass has a higher complication rate than laparoscopic sleeve gastrectomy, yet Roux-en-Y produces better long-term weight loss outcomes and has a superior record of continued hypertension resolution five years post surgery.13
Moreover, patients who have binge eating disorder or who use food as a primary emotional coping mechanism are more likely to regain weight post surgery. Binge eating disorder or other loss-of-control eating behaviors may be triggered by the postoperative dietary guidelines.14,15 Results of a 2017 review suggest that despite substantial weight loss and physical health improvements experienced post surgery, some psychological problems, probably linked to a preexisting disordered relationship with food, remain.16
According to Severson, it’s important for dietitians and patients to remember that medications and surgery are always an adjunct to diet and lifestyle modifications. “Diet and lifestyle changes are quite effective on their own, but, as we know, making significant sustainable changes is challenging for many people, and some people have hypertension that isn’t controlled with diet changes alone,” she explains.
Severson emphasizes that poor MNT insurance coverage for hypertension means long-term support from a dietitian frequently isn’t an option for patients with hypertension, despite the fact improvements in blood pressure are greater with ongoing dietitian visits. “Medications to manage cardiovascular risk factors, such as blood pressure, lipids, and obesity, are all designed to work in conjunction with diet and lifestyle changes, and the combination is more powerful than either on its own,” she notes.
Willer adds that when evaluating “obesity-related” health risk factors—and changes to those risk factors in weight loss intervention studies—it’s important to remember that the larger-bodied people in the control groups may have factors contributing to elevated blood pressure unrelated to having more body fat—for example, weight stigma and avoidance of preventive health care. So when the intervention group lowers blood pressure, how does one know it’s because of the weight loss itself? “Until control groups are filled with people who are nondieting, with low internal weight stigma, and who are receiving timely and effective health care—not triaged, delayed, or denied on the basis of BMI—then there’s no reasonable comparator for weight loss intervention groups,” Willer says.
— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times, owner of Nutrition by Carrie, and author of Healthy for Your Life: A Holistic Guide to Optimal Wellness.
1. Estimated hypertension prevalence, treatment, and control among U.S. adults. Million Hearts website. https://millionhearts.hhs.gov/data-reports/hypertension-prevalence.html. Updated March 22, 2021.
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