Low Blood Pressure and The Ketogenic Diet
By Todd Gamel, RN
Many people after being on a ketogenic diet for a couple of weeks begin to notice that their blood pressure readings begin to drop, some more significantly than others. This is a good thing, especially if you have been diagnosed with hypertension (high blood). Unfortunately a side effect of lower blood pressure is that some people who are on anti-hypertensive (blood pressure) medications may experience what is know as orthostatic hypotension. Orthostatic hypotension is a condition in which your blood pressure suddenly drops when you make quick movements, such as standing up quickly, but most commonly when squatting and or bending over and or then standing up. Typically with orthostatic hypotension your systolic blood pressure (SBP), the top number, drops about 20mmHg and or your diastolic blood pressure (DBP), the bottom number, drops by about 10mmHg when you make quick shifts such as standing once you have been bent over or squatting down. This sudden drop in blood pressure can cause dizziness and can make you unsteady on your feet.
As I mentioned, decreasing blood pressure is not an uncommon adverse effect of the ketogenic diet. As you lose weight there is less vascular resistance and your body does not have to work as hard to circulate your blood. Less resistance means that your blood pressure will (or should) slowly decrease over time. Now many people have rapid weight loss when on a ketogenic diet, and therefore begin to develop orthostatic hypotension as a result. It’s not just the weight loss however, most of you will experience a rapid shift in fluids due to diuresis (high amounts of urination) due to the body’s chemical changes when starting a ketogenic diet. The effects of this diuresis can lead to hypovolemia (low volume) which also decreases vascular resistance, which is another common cause of hypotension. This means that you need to make sure you are getting plenty of fluids including the electrolytes sodium, potassium, and magnesium. Overtime your body should adjust to your new blood pressure norm as it attempts to find a state of homeostasis (equilibrium). For most people this is not a problem unless of course you are taking oral anti-hypertensives.
Anti-hypertensives And Keto
This is why in general, most MD’s are not overly concerned about orthostatic hypotension unless you actually start to have frequent episodes of dizziness and or syncope (passing out), which is a cause for concern.. Generally the solution is to change your prescribed anti-hypertensive medication to a lower dose, which is a good thing. Hack, you may even get to get off all of your blood pressure medications, as both I and many tens of thousands of people who follow this way of keto eating do.
As an example when I first started my ketogenic journey , I was on the anti-hypertensive lisinipril 40mg once a day for my blood pressure. I monitored my BP everyday, when I started this way of eating (WOE) and when I noticed the trend in my blood pressure lowering and started to have some slight dizzy spells, I lowered my BP medication. Now I am not advocating that anyone adjust their medications on their own, you should definitely see your MD, and work with them if you are having any of these symptoms. As a medical professional of 14 years, I felt that I had the personal knowledge to make my own decisions when it came to adjusting my own blood pressure medication. Having said that, there is an old saying that “a doctor that is his own patient is a fool”, or something to that affect. Anyway, I tapered my medication over about two months until I was able to get off my anti-hypertensive medications and have remained off of them. Over time my blood pressure normalized and I no longer have any effects of orthostatic hypotension. And, yes, I followed up with both my family practice physician, and my endocrinologist regarding my blood pressure mediations.
Monitoring You Blood Pressure
For most people who do not have high blood pressure, orthostatic hypotension is not a problem, but what if you are taking oral anti-hypertensives you will most likely experience this side effect. The more medication(s) you take, and the higher the doses, the more likely hood you will experience this issue. So, once you begin on a ketogenic diet it is very important that you monitor your daily blood pressures when you first embark on this way of eating (WOE), this is especially true if you are taking anti-hypertensive medications. I recommend that you buy an automated blood pressure cuff, the wrist type that can be found at your local big box retailer or online. A good one costs about $50 and they are pretty accurate (even some doctor’s offices use these).
If you haven’t started keto yet, and are thinking about it, I recommend that you take a weeks worth of blood pressure readings so that you have a baseline to compare your blood pressure readings with once you start this WOE. This will help you to determine how your keto eating plan is affecting your blood pressure.
If you have already started the ketogenic diet, that’s ok, just start taking daily blood pressure readings so that you can monitor your progress. Once you have a way to check your blood pressure (BP) readings, start out by taking them after you first get up and just before you go to bed. This is especially important if you are having symptoms such as dizziness or light headedness. Each time you experience a bout of hypotension take a BP reading and record the result along with the dosage of the medication(s) that you are taking so that your physician can help you manage these symptoms. If you start to have these symptoms and you are on anti-hypertensive medications then you need to make an appointment with your MD so that they can help you to adjust your blood pressure medications. DO NOT, I repeat, DO NOT make any changes to your blood pressure medications without consulting your physician.
Here are the ranges of blood pressure as described by the American heart Association (AHA) on their website. The systolic is the first, or top number on your blood pressure monitor, and the diastolic is the second or bottom number on your blood pressure monitor.
Low* (Systolic less 90, Diastolic less than 60)
Normal (Systolic less 120, Diastolic less than 80)
Elevated (Systolic 120 – 129, Diastolic less than 80)
Hypertension Stage 1 (Systolic 130 – 139, Diastolic 80 – 89)
Hypertension Stage 2 (Systolic 140 or higher, Diastolic 90 or higher)
Hypertensive Crisis (Systolic 180 or higher, Diastolic 120 or higher)
*There is no agreed upon specific number as long as you are not having any symptoms.
As I mentioned, decreasing blood pressure is not an uncommon adverse effect of the ketogenic diet. In fact, I would not categorize it as an adverse affect, but as an expected outcome. One of the many benefits of weight loss is that it decreases the demand on the heart to circulate your blood volume which helps to lower your blood pressure, and that’s a good thing. If you are currently not on anti-hypertensives then you should have no problems, but for those of you who take blood pressure lowering medications, you have to take care and monitor for the possible signs and symptoms of orthostatic hypotension.
Remember, if you start to have any signs and symptoms of orthostatic hypotension make sure that you consult your physician or heath care professional before making any changes to your medications. They have studied and trained for many years and can safely help you to make the transition of lower your medications and hopefully one day like me you will be able to stop all of your blood pressure medications. Good luck, and stay keto strong my friends.