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How does intermittent fasting affect blood pressure?

Hypertension is a serious health issue. Hoppefuly, intermittent fasting can help you treating it, here is why and how.
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Today we talk about a serious health issue that affects nearly every other adult: high blood pressure.

You’ll learn why hypertension is so dangerous and how intermittent fasting can help you get it under control.

Ready? Let’s dive in.

Written by
Sarah Neidler, PhD
Freelance Science and Medical Writer

What is blood pressure?

Blood pressure is the pressure with which the circulating blood exerts against the blood vessels. The higher the blood volume, the higher the pressure. 

You can compare it with a balloon filled with water. The more water you add, the higher the pressure. If the pressure becomes too high, the balloon may burst. Your blood vessels won’t burst, but high pressure can still damage them. This is the reason why high blood pressure is dangerous (more on this further down).

Blood pressure is measured in millimeters of mercury (mmHg) and is represented by two numbers.

  • The first number indicates systolic pressure. This is the maximum pressure during one heartbeat.

  • The second number indicates diastolic pressure. This is the minimum pressure between two heartbeats.

What is a healthy blood pressure?

It is crucial for health that the blood pressure is within a specific range. Normal, healthy blood pressure is between 90/60 mmHg and 120/80 mmHg.

Having blood pressure that is too low (hypotension) can lead to dizziness, fatigue, and fainting. In the worst case, it can cause circulatory collapse–when blood circulation decreases to the extent that tissues and organs are no longer adequately supplied with oxygen. 

Having high blood pressure (hypertension) is defined as pressure above 130/80 mmHg. 

Hypertension is much more common than hypotension. Nearly half of American adults (45%) have hypertension.

Why is high blood pressure dangerous?

Monitor placed on the finger to measure blood pressure.

Remember the balloon? High blood pressure creates mechanical stress on the arterial walls. This damages the interior of the blood vessels. Damage to the blood vessels increases the risk of atherosclerosis–a condition when the blood vessels become thick and stiff with cholesterol plaque build-up. When a plaque ruptures, blood clots can block blood flow to vital organs, such as the heart and the brain.

High blood pressure is the biggest risk factor for heart disease. The risk of cardiovascular mortality doubles for every 20 mmHg increase in systolic and every 10 mmHg increase in diastolic pressure.

Heart disease, in turn, is the most common cause of death. Around 600,000 Americans die each year from heart disease.

What makes hypertension so frightening is that it has no symptoms. For this reason, it is called the “silent killer”.

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What causes hypertension?

Hypertension is strongly associated with overweight and obesity. In turn, losing weight is known to lower blood pressure...

Hypertension has many different causes, but they are not yet fully understood.

But insulin resistance seems to be an important factor, and the mechanism by which it affects blood pressure is well understood. Insulin is a blood sugar-lowering hormone. Insulin resistance means that cells become less sensitive to insulin. The pancreas then has to produce more insulin to control blood pressure. Insulin resistance is the underlying cause of type 2 diabetes. 

How does insulin resistance cause hypertension?

Insulin resistance accompanies high insulin levels, and high insulin inhibits salt excretion by the kidneys. Difficulties excreting salt lead to a higher salt concentration in the blood. Because salt binds and attracts fluids, this increases the blood volume–and a higher blood volume raises blood pressure.

Intermittent fasting and blood pressure

Stethoscope measuring vitals.

Intermittent fasting is very effective in improving insulin resistance within a short time. It is, therefore, not surprising that intermittent fasting also helps to decrease blood pressure.

This has been shown in multiple intermittent fasting studies, and the results are very consistent...

However, there are a few exceptions. Some studies could not observe a drop in blood pressure through intermittent fasting.

But by having a closer look at the studies, there is an easy explanation: The study participants were not hypertensive prior to intermittent fasting.

So, intermittent fasting lowers the blood pressure only when it’s elevated. For this reason, it’s better to say that intermittent fasting normalizes blood pressure.

That’s good news when you think about it. That means that in people with normal blood pressure, intermittent fasting won’t cause hypotension. 

But be careful when you take blood pressure lowering medications. In that case, intermittent fasting can indeed cause a potentially dangerous drop in blood pressure. That doesn’t mean that you shouldn’t practice intermittent fasting when taking blood pressure medications: it’s a powerful method to get you off your medications. But you should talk to your doctor about how to adjust the dose of your medications before starting intermittent fasting.

Is the blood pressure lowering effect due to weight loss?

We mentioned earlier that losing weight is known to lower blood pressure. Intermittent fasting, in turn, is very effective for weight loss.

So is the blood pressure normalizing effect of intermittent fasting due to weight loss?

A study assessed whether the health benefits of intermittent fasting, such as improving insulin resistance and lowering blood pressure, have something to do with weight loss.

For this purpose, men with prediabetes (and hypertension) practiced 18/6-fasting for five weeks (they ate only within a six hour period every day and abstained from food for the remaining 18 hours). But the study protocol ensured that the probands did not lose weight: As soon as the weight started to go down, the calorie intake was increased.

Surprisingly, intermittent fasting could significantly lower blood pressure and improve other health markers despite the lack of weight loss.

So, even if you don’t want to lose weight, intermittent fasting still offers many health benefits.

Bottom line

Hypertension is the biggest risk factor for heart disease, and intermittent fasting is very effective in getting high blood pressure under control. This demonstrates again that intermittent fasting not only helps to lose weight–it has many more benefits to offer. It also helps to improve insulin resistance, which increases the risk of many chronic conditions.

If you look for support during your intermittent fasting journey, we recommend joining our intermittent fasting community for women


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