Weight loss and blood pressure

Hmm, that’s an interesting question. When I counsel patients on controlling blood pressure I mention weight loss but don’t perseverate on it because of the general futility of of achieving lasting weight loss. Most diets deliver only modest weight loss and that weight loss is depressingly short lived:
The figure above is the primary results from a trial of various strategies to preserve weight loss. 1,685 patients were enrolled, only 1,032 lost the require 10 lbs to begin Phase 2. In Phase 2 patients were randomized to 1) minimal intervention 2) web-based interaction 3) monthly contact with an interventionist. Patients with monthly contact regained 3 lbs less than the patients with self-directed maintenance. Svetkey et al. Comparison of strategies for sustaining weight loss: the weight loss maintenance randomized controlled trial. JAMA (2008) vol. 299 (10) pp. 1139-48 (PDF)

Second study looking at Weight Watchers compared to a self-help program for weight loss. Same pattern, modest weight loss followed by rebound to regain much of the lost weight. Heshka et al. Weight loss with self-help compared with a structured commercial program: a randomized trial. JAMA (2003) vol. 289 (14) pp. 1792-8 (PDF)

I focus my limited office time on changing patients’ diet to reduce blood pressure. I recommend the DASH diet (PDF) to all of my patients without significant metabolic bone disease or hyperkalemia because I believe the data shows that it is the most effective life-style intervention to ameliorate hypertension. Unfortunately those two exclusions (bone disease and potassium) exclude many of my patients. I usually don’t recommend the low sodium version of of DASH because I feel that the reduction in palatability is not supported by the rather modest additive effects (an additional 3 mmHg reduction in SBP). Most of my patients recognize that they eat too much and have been trying to reduce calories, and lose weight for years prior to seeing me. I feel that by discussing the DASH diet and not rehashing the same tired dietary advice that every doctor has been promoting, I provide them with a novel view of dietary changes that they are willing to try.

Still, I think The Kidney Group has an interesting question, what is more important weight loss or diet changes?

NephSAP recently reviewed hypertension. On page 98 they had this table which compared various lifestyle interventions and their effect on blood pressure:
Unfortunately they grouped diet and weight loss in one group so it does not allow me to separate out the effect of changing diet from changing weight. Regardless, the effect on blood pressure looks modest compared to the findings of the DASH diet or DASH sodium intervention. From the abstract of the DASH-Sodium trial (PDF):

As compared with the control diet with a high sodium level, the DASH diet with a low sodium level led to a mean systolic blood pressure that was 7.1 mm Hg lower in participants without hypertension, and 11.5 mm Hg lower in participants with hypertension.

The Archive published this meta-analysis (PDF) in 2008 looking at weight loss by diet or drugs with respect to mortality and blood pressure control.

They found that weight loss did result in blood pressure reductions but the reduction was modest. Additionally not all methods were equal, with silbutamide (Meridia) resulting in an increase in blood pressure despite being effective at reducing weight. They were unable to find any studies which showed a reduction in weight reducing mortality.

The above systemic review mentioned that the TONE study was one that was particularly well done. The TONE trial (PDF) was published in JAMA in 1998 and compared sodium restriction to weight loss to usual care in a two by two factorial design. The enrolled 585 obese patients to be randomized to either weight loss, no weight loss, salt restriction or not. Another 390 were randomized to either salt restriction or usual diet.
The investigators achieved nice separation of the groups with regard to weight loss. The study began with every patient weaning off their antihypertensive medication and the primary end-point was the fraction resuming their pharmacologic blood pressure medications and the time to resumption. Weight loss was more effective than no intervention and about equally efficacious as sodium restriction:

Note the lower starting blood pressure for sodium intake, this accounts for some of the difference in the effect on blood pressure.

Though TONE showed no difference between weight loss and sodium restriction, I feel that diet is probably more important because sodium restrictionis not the most effective dietary change to reduce blood pressure, the DASH diet is. I feel that if the TONE trial was rerun with the DASH diet replacing sodium restriction we might see that diet is more important than weight loss.

One thing I am doing in my clinic more and more is recommending bariatric surgery. Medical and behavioral changes have a poor track record at providing lasting and significant weight loss. Bariatric surgery shows lasting weight loss 10 years out and it allows patients to recover from hypertension and diabetes. Sjöström et al. Lifestyle, diabetes, and cardiovascular risk factors 10 years after bariatric surgery. N Engl J Med (2004) vol. 351 (26) pp. 2683-93. (PDF)

6 Replies to “Weight loss and blood pressure”

  1. You might be interested in a concept called “Health at Every Size”. Its most prominent proponent is Linda Bacon, a nutrition professor and researcher. HAES, as you put it, recognises that weight loss programs are depressingly futile, takes weight loss as a goal out of the health equation and encourages genuinely healthy eating and sustainable, enjoyable physical activity along with boosting self-esteem. The main study is here:
    http://www.ncbi.nlm.nih.gov/pubmed/15942543?log$=activity and more info at http://www.lindabacon.org/about.html

    Special medical diets like DASH, gluten-free, etc are easily incorporated into the philosophy as it encourages mindful eating without the guilt of dieting.

    And advice which is often given by kidney organisations which may be useful for CKD, various nephropathies, etc, isn’t necessarily useful for PKD. As I’m sure you know, weight loss won’t help PKD, as cyst growth is from cAMP action set off by vasopressin, and the renin-angiotensin-vasopressin system is the source of hypertension in PKD. Hence current trials on high-dose ARDs + ACEII inhibitors together, along with the one on Tolvaptan. The DASH diet might not do anything for PKD people either, depends on if they have other, concurrent causes of hypertension. I know it didn’t do anything for me (I have PKD, about 50% function) and I don’t do well on a low-fat diet; low protein, moderate carbs, and higher fat works for me. I eat “wholesome” fats like olive oil, coconut oil, fish oil, nuts and whole dairy. All my lab results seem much better for it.

    And from personal experience, my advice on blood pressure is: Make sure the nurse or doctor is using the correct size cuff! I think there’s more than one study showing at least 30% of obese people labelled hypertensive were misdiagnosed because the cuff was too small. That’s especially important when you have kidney disease.

  2. Sorry, I meant the renin-angiotensin-aldosterone system up there. It’s very late where I am and I should be in bed. Brain fail!

  3. That’s more like a blog post than a comment. Thanks for your insight. Whenever I meet with PKD patients I always go over the big three trials I am most interested in:
    • ACEi+ARB
    • Tolvaptan
    • M-Tor hypothesis with rapamune

    Are you enrolled in any of these trials? Are you on rapa or ACE+ARB off label?


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