Intermittent fasting, which involves limiting your eating to a certain window of time, is associated with several health benefits, including lower blood pressure. If you have high (hypertension) or low blood pressure (hypotension), you may then wonder how fasting will affect your levels and if you need to take any special precautions.
Although current research suggests promising blood pressure benefits from intermittent fasting, it’s important to learn how to monitor your numbers and practice fasting safely. In this article, we’ll explore how intermittent fasting affects blood pressure, how blood pressure medications may play a role, and how fasting and heart health can occur together.
Intermittent fasting may help lower blood pressure by improving insulin sensitivity, reducing visceral fat, and supporting blood vessel function. However, blood pressure can also drop too low during fasting, especially early on or if you take blood pressure medications. Monitoring hydration, electrolytes, and symptoms is important. A balanced approach with adequate nutrition and gradual weight loss supports heart health and stable blood pressure.
How Intermittent Fasting Affects Blood Pressure
Intermittent fasting can reduce blood pressure in several ways, often as a result of lower insulin levels.
Lower Insulin & Improved Vascular Function
During fasting times, insulin levels, the hormone that regulates blood sugar, decrease. When you go a longer time without food, insulin levels reduce in response. When insulin reduces, it calms the nervous system and allows blood vessels to relax. When this happens, blood and fluid moves more efficiently through the body and vascular system, which can naturally lower blood pressure.
Weight Loss & Visceral Fat Reduction
As a registered dietitian, I often see many are interested in fasting as a weight loss method. And because it creates a shorter eating window, I’ve seen intermittent fasting naturally reduce calorie intake for many of my clients. Specifically, research suggests intermittent fasting may not only support weight loss, but can help reduce visceral fat. This is the more dangerous fat surrounding internal organs, which can be a big driver of high blood pressure.
Studies show that losing even as little as 5% of body weight, such as 10 lbs for a 200-lb person, has the power to lower blood pressure.
Losing as little as 5% of body weight can lower blood pressure.
For a 200-lb person, that is about 10 lbs. Intermittent fasting may help achieve this through natural calorie reduction and visceral fat loss.
A Process Called Natriuresis Occurs
As mentioned above, abstaining from food for a period of time decreases insulin levels. When insulin levels drop, the kidneys release more sodium, which pulls water out of the body along with it. This fluid-reducing process is called “natriuresis,” and it often occurs in the first few weeks of fasting as a result of these fluid and electrolyte shifts.
When this happens, blood volume decreases, which can cause a drop in blood pressure. In some cases these drops can be significant, particularly in people who have low blood pressure to begin with or who take blood pressure medications. This can temporarily lead to feelings of dizziness if the right precautions are not in place.
Gut Microbiome Changes
While not as readily known and understood, fasting also appears to regulate blood pressure via its effects on the gut microbiome. Research suggests that fasting can shift the balance of bacteria in the gut, changing the types of compounds they produce in ways that may help lower blood pressure. These changes may improve how the body regulates inflammation and blood vessel function, which play important roles in maintaining healthy blood pressure levels.
Does Fasting Lower Blood Pressure Long-Term?
Research on the short-term effects on blood pressure are promising, but the long-term effects are still being explored. However, the American Heart Association notes routine fasting can have a positive impact on cardiac health overall, which can include blood pressure as one benefit. By fasting even somewhat regularly, the short term mechanisms can be activated repeatedly to deliver ongoing benefits.
Fasting and hypertension benefits tend to be stronger in:
Those with obesity or overweight. Individuals who are overweight and lose weight are likely to experience the greatest benefits with intermittent fasting. This is due to the ability of fasting to reduce abdominal fat, a risk factor for elevated blood pressure.
Those with insulin resistance. People who already have insulin resistance may experience more profound blood pressure benefits as well. This is because insulin levels reduce during fasting, which can lower blood pressure and improve insulin sensitivity to a greater extent than someone who has normal insulin sensitivity to begin with.
People with elevated baseline blood pressure. The higher the baseline blood pressure, the more noticeable a reduction you’ll likely see from fasting.
In general, blood pressure improvements are often tied to the extent of weight loss, improvements in insulin sensitivity, and reduced inflammation in the blood vessels.
Low Blood Pressure During Fasting: What to Watch For
While fasting can bring blood pressure to a more desired level, it can sometimes drop too low in some cases. However, there are clear signs to look for and ways to prevent low blood pressure during fasting.
Common causes include reduced insulin and electrolyte/fluid shifts, inadequate fluid intake or dehydration, rapid calorie restriction, and blood pressure medications that have not been adjusted for fasting.
Being proactive and planning ahead for these changes are key to reducing the risk of these symptoms. If you take blood pressure medications, always speak to your doctor first before starting a fasting plan to see if the timing or dose need to be adjusted. The Fasting App by Municorn is a helpful tool to help you note any changes you’re seeing so you can address them.
How to Monitor Safely
Here are some checkpoints to consider in order to monitor your blood pressure control.
Before Starting Fasting
Monitor your baseline blood pressure readings if you have low or high blood pressure. Review your medications with your provider or any abnormal readings to determine the best plan.
During Fasting
Check your blood pressure several times a week the first few weeks to see how it responds to your fasting regimen. Track any symptoms in the Fasting App and monitor your food and fluid intake to see what’s working.
If Blood Pressure Drops Too Low
Reassess your hydration. Are you meeting your daily needs? It’s also important to check sodium and electrolyte intake to see if you are getting in enough salt and electrolyte-rich foods such as fruits, vegetables, beans, nuts and seeds.
If unsure, contact your healthcare provider to evaluate your medications and lifestyle.
Blood Pressure Medications & Fasting: A Critical Conversation
Since blood pressure can improve quickly with fasting, it can affect those on blood pressure medications. If you take the following medications, speak to your doctor before fasting to see if things need to be adjusted:
- Diuretics (e.g., Lasix, Bumex)
- ACE inhibitors (e.g., Zestril, Lotensin)
- ARBs (e.g., Cozaar, Benicar)
- Beta blockers (e.g., Lopressor, Coreg)
It’s important to have open communication with your prescribing doctor, have a baseline review before starting fasting, and have ongoing monitoring if you have any questions or concerns. If your blood pressure goes low, never adjust your medication without consulting your provider.
Other Precautions to Consider
As a general precaution, it’s also good to speak to your doctor before starting intermittent fasting if you have uncontrolled hypertension, advanced cardiovascular disease, chronic kidney disease (as flushing out of electrolytes and fluid can further strain the kidneys), a history of fainting or low blood pressure, or if you are pregnant or breastfeeding.
In addition, if you are losing more than 2 pounds per week, speak to a registered dietitian or your physician about a more gradual approach for optimal health.
Dietitian Tips to Support Healthy Blood Pressure While Fasting
These simple habits can support healthy blood pressure while fasting and help you feel your best.
Stay well hydrated
Fluids help maintain adequate blood volume and healthy circulation, both of which influence blood pressure. When you become dehydrated and aren’t consciously prioritizing fluid intake, blood pressure can drop too low, leading to dizziness or fatigue. Aim to drink water consistently throughout fasting and eating windows, and set regular reminders if you tend to forget.
My clients often find it helpful to leave a water bottle or thermos front and center in places they’re likely to be, so hydration stays top of mind. Adding natural flavor like lemon, lime, or an electrolyte powder can also help encourage hydration and support electrolyte balance. Just remember that during fasting windows all beverages need to be calorie-free.
Avoid aggressive sodium restriction unless prescribed
While overdoing it on sodium can raise blood pressure, you still need some in order to maintain fluid balance in your blood vessels. Because of this, cutting sodium too drastically during fasting can cause blood pressure to dip too low. This may be more likely if you are also drinking a lot of plain water (without sodium or other electrolytes) or losing weight rapidly.
Unless your healthcare provider has recommended a strict sodium restriction, it’s generally suggested to meet the daily recommendation of 2300 mg for sodium, or 1 teaspoon of table salt, to help support stable circulation.
Include potassium-rich foods during eating windows
Potassium helps balance sodium levels to keep blood pressure in a healthy range. Including potassium-rich foods like leafy greens, beans, avocados, bananas, and sweet potatoes during eating windows alongside moderate sodium intake can help stabilize blood pressure without causing it to drop too low. These foods also provide fiber and nutrients that support heart health overall and can be satisfying if you’re trying to control your calorie intake.
Strength train 2-3x/week
Regular strength training supports healthy blood pressure by improving blood vessel function, even from just a single bout of exercise. Building and maintaining muscle mass also helps support a healthy metabolism and circulation, which can prevent the sharp drops in blood pressure that sometimes occur with rapid weight loss. Even short sessions of resistance exercises – like bodyweight movements or light weights – can help maintain these benefits during fasting, and support metabolic health in the process.
Avoid extreme calorie restriction
While fasting naturally reduces eating hours, combining it with very low calorie intake can increase the risk of low blood pressure, fatigue, and nutrient deficiencies. Eating balanced meals during your eating windows – with adequate protein, fiber, healthy fats, and complex carbohydrates – helps maintain energy levels, stable circulation, and more sustainable weight loss.
If weight loss is one of your goals, aim to do it gradually. I recommend (and research suggests) a rate of 1-2 pounds per week, which allows the cardiovascular system to adjust while still improving blood pressure over time. This approach also supports muscle preservation and makes fasting easier to maintain long term.
Key Takeaways
Intermittent fasting blood pressure improvements are just one factor demonstrating the cardiovascular benefits of this way of eating. Fasting may also improve triglycerides, insulin resistance, and visceral fat – all of which support long-term heart health. And when you need a little extra support and accountability, the Fasting App can help keep you on track.
Does intermittent fasting lower blood pressure?
It can. Intermittent fasting may lower blood pressure by reducing insulin levels, promoting visceral fat loss, and improving blood vessel function. The effect tends to be stronger in people with obesity, insulin resistance, or elevated baseline blood pressure. However, the degree of improvement depends on factors like diet quality, weight loss, and individual health status.
Can fasting make blood pressure too low?
Yes, especially in the first few weeks. Fasting triggers natriuresis, a process where the kidneys release more sodium and water, reducing blood volume. This can cause dizziness, lightheadedness, or fatigue. The risk is higher if you are already on blood pressure medications, are dehydrated, or are restricting calories aggressively. Monitoring your levels and staying hydrated helps prevent this.
Should I take blood pressure medication while fasting?
Never stop or adjust blood pressure medication without consulting your doctor. Because fasting can lower blood pressure on its own, the combined effect with medication may cause it to drop too low. Talk to your prescribing doctor before starting fasting so they can evaluate whether timing or dosage adjustments are needed.
How much weight do I need to lose to lower blood pressure?
Research suggests that losing as little as 5% of your body weight can produce meaningful blood pressure reductions. For a 200-pound person, that is about 10 pounds. Gradual weight loss of 1-2 pounds per week through moderate fasting and balanced nutrition tends to produce more sustainable cardiovascular improvements than rapid weight loss.
What should I eat during my eating window to support blood pressure?
Focus on potassium-rich foods like leafy greens, avocados, bananas, beans, and sweet potatoes to help balance sodium levels. Include lean protein, fiber, and healthy fats at each meal. Unless your doctor has prescribed strict sodium restriction, aim for about 2300 mg of sodium daily to maintain fluid balance. Avoid extreme calorie restriction, which can cause blood pressure to drop too low.
