Dr. Angela Ryan Lee is board certified in cardiology and internal medicine. Her professional interests include preventive cardiology, medical journalism, and health policy.
Anthony C. Pearson, MD, FACC, is a board-certified cardiologist in St. Louis, Missouri.
Intermittent fasting has become a popular dietary trend that benefits blood pressure, weight loss, inflammation, cholesterol, and blood sugar.
This article focuses on the relationship between fasting and blood pressure, reviews the problems that come with high blood pressure, and looks at how fasting may be one way to help lower it.
Peter Dazeley / Getty Images
High blood pressure, or hypertension, affects nearly half of all Americans and increases the risk of several severe conditions. People with high blood pressure are more at risk for the following:
If you've been diagnosed with high blood pressure, there are many ways to lower it and decrease your risk. Lifestyle changes are a big part of controlling blood pressure, particularly dietary changes.
While choosing nutritious foods and lowering salt and processed food intake have shown to be beneficial, research also suggests that certain fasting patterns may lower blood pressure, too.
Various fasting methods have been shown to lower blood pressure, with one study showing a dramatic decrease of 11 points. Studies are ongoing to determine precisely how fasting lowers blood pressure. It appears that several mechanisms are involved in this relationship.
Firstly, caloric restriction has been shown to lower blood pressure. Fasting is often associated with an overall lower calorie intake, which can help explain some of its effects.
Studies also suggest that while fasting, the nervous system is in a more relaxed state, known as parasympathetic tone. This is in contrast to a state of heightened alertness, or sympathetic tone, associated with increased blood pressure.
Fasting may even affect blood pressure through the gut microbiome, the population of bacteria living in the gastrointestinal system that has effects ranging from digestion to the immune system.
Weight changes and water loss can also lower blood pressure, as seen in studies of people observing the Islamic practice of fasting during the holy month of Ramadan. During this time, observers of the religious fast do not eat or drink during daylight hours. One study found that people who fasted during Ramadan experienced lower blood pressure independent of changes in weight or body water content.
Since fasting can significantly lower blood pressure, individuals with low blood pressure need to carefully monitor that it doesn’t drop too low. Also called hypotension, this condition can cause symptoms of lightheadedness, dizziness, fatigue, and fainting.
Some people may have an exaggerated response to fasting. The following people may be at higher risk of complications from fasting:
Prolonged fasting can also lead to hypotension due to dehydration, so ensuring adequate hydration is essential. Discuss fasting plans with your healthcare provider, especially if you’re taking blood pressure medications.
In addition to lowering blood pressure, intermittent fasting has been shown to have the following beneficial effects:
Intermittent fasting may also help improve longevity by increasing lifespan. Rates of heart failure appear to also be lower, according to preliminary studies.
If you are interested in fasting for its health benefits, it's important to discuss your plans with a healthcare provider; they can provide guidance on the risks and benefits of your specific circumstances and recommend medication adjustments if needed.
First, choose a fasting plan. Plans vary by the length and timing of fasting. Depending on the specific intention for fasting, the plan may allow drinking fluids throughout the day. In either case, plan ahead to ensure you avoid dehydration and hypotension.
During periods of eating, choose foods that will provide substantial nutrition. Avoid simple sugars that can cause a sugar crash, and opt for a combination of complex carbohydrates, fat, and protein to prevent muscle wasting.
High blood pressure is a common and serious condition that increases the risk of heart disease and stroke. Studies have shown a beneficial effect of fasting on lowering blood pressure. Fasting also has benefits on weight, diabetes, and cholesterol. A safe fasting plan should include a discussion with your healthcare provider, plans for any medications you take, and a commitment to staying hydrated and getting enough nutrition.
If you are among the nearly 50% of Americans with high blood pressure, you may be looking for ways to lower blood pressure. If you decide to try intermittent fasting, make sure to discuss your plans with a healthcare provider first.
Studies have shown that intermittent fasting can help lower blood pressure.
Blood pressure regulation is complex, and many situations can cause low blood pressure. Dehydration, medications, infection, and certain heart conditions are just a few things that can lower blood pressure. Symptoms of low blood pressure are consistent despite the cause and include lightheadedness, fatigue, and in severe cases, loss of consciousness.
Skipping meals, such as intermittent fasting, can lower blood pressure. The effect appears to be temporary, with blood pressure returning to its usual levels after fasting. Low blood pressure while fasting also appears to be independent of dehydration, which can lower blood pressure.
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Angela Ryan Lee, MD, is board-certified in cardiovascular diseases and internal medicine. She is a fellow of the American College of Cardiology and holds board certifications from the American Society of Nuclear Cardiology and the National Board of Echocardiography. She completed undergraduate studies at the University of Virginia with a B.S. in Biology, medical school at Jefferson Medical College, and internal medicine residency and cardiovascular diseases fellowship at the George Washington University Hospital. Her professional interests include preventive cardiology, medical journalism, and health policy.
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