Intermittent fasting (IF) may not be the first thing that comes to mind when you think of heart health, but recent research shows that it can help reduce several cardiovascular risk factors, including high blood pressure. For many, it is an inexpensive, low-risk, and easy-to-follow way to improve health.
Intermittent fasting refers to the practice of consistently alternating times of eating with times of fasting, such as the 5:2 method, which incorporates two days of severely calorie-restricted eating with five days of nonrestricted eating, or alternating eating and noneating days.
The most commonly used method of intermittent fasting is time-restricted eating (TRE). TRE is a daily regimen in which all of the day’s food is consumed within a set timeframe—for example, consuming meals within an eight-hour window, for instance between 9 a.m. and 5 p.m., and then fasting for 16 hours. During fasting times, only water or clear, noncaloric liquids such as coffee or tea are consumed.
Intermittent fasting has skyrocketed in popularity in recent years, largely because of celebrities and bodybuilders singing its praises on social media, but a growing body of research is also supporting its use for working toward health goals that don’t necessarily include weight loss or muscle-building. The list of health benefits now associated with intermittent fasting includes cell repair and anti-aging mechanisms, reduced free radical production, improved glucose regulation, and stress reduction, among others. A review in the Dec. 26, 2019, issue of the New England Journal of Medicine also describes a number of potential cardiovascular benefits of intermittent fasting, including reductions in blood pressure.
Just how fasting serves to lower high blood pressure—a potentially serious condition that affects nearly half of the adult U.S. population—isn’t entirely clear. And while it’s true that calorie-restricted diets have been shown to lower blood pressure, and that fasting often results in reduced caloric intake, many experts are now shifting their focus to the role of insulin.
Intermittent Fasting to Reduce Insulin Resistance
Recent research has focused on the fact that intermittent fasting can reduce insulin resistance—a common condition in which the pancreas produces too much insulin (hyperinsulinemia) in an effort to lower high blood sugar levels. The body’s cells eventually “resist” the flood of insulin by no longer responding normally and removing glucose from the blood. This then signals the pancreas to produce even more insulin.
High insulin levels are known to inhibit salt excretion by the kidneys, increasing the risk of high blood pressure. A review published in the December 2012 issue of the American Journal of Physiology found that, across several animal studies, insulin had a sodium-retaining effect in diabetic subjects.
Excess salt is problematic because it attracts fluid. The American Heart Association states: “Too much sodium in your system promotes water retention in the bloodstream. Over time, the extra blood volume of blood can stress and stiffen blood vessels, making the heart work harder to maintain blood flow.”
Intermittent fasting effectively lowers insulin levels, which reduces insulin resistance and can indirectly lead to reduced blood pressure. Going without food for eight or more hours also allows “metabolic switching” to take place—in the absence of excess glucose to use for energy, the body uses energy stored in fat cells instead. Cleveland Clinic explains: “When we don’t eat for a period of time, insulin isn’t needed, and our blood insulin levels drop. This signals our fat cells to release sugar to be used as energy. When insulin levels drop far enough, we burn enough fat to lose weight.”
There are likely other factors at play, too. Rhianna Jones, a registered nurse at CanXida.com, told The Epoch Times: “Intermittent fasting often leads to weight loss and improved insulin sensitivity, both of which can contribute to lower blood pressure. Additionally, fasting periods may reduce oxidative stress and inflammation, which are known factors in hypertension. Some studies suggest that fasting can also enhance the production of nitric oxide, a molecule that helps relax blood vessels, thus promoting better blood flow and lower blood pressure.”
Intermittent fasting isn’t right for everyone though. Pregnant or breastfeeding women shouldn’t fast. And those struggling with eating disorders, or people with underlying medical conditions such as diabetes or heart conditions, should check with their doctors before beginning any type of fasting regimen.
Timing of Fasting Makes a Difference
For those who do want to give intermittent fasting a try, there are a few details to keep in mind. First of all, the timing of food intake seems to matter. A May 2018 study in the journal Cell Metabolism found that, in men with prediabetes, restricting food intake to earlier in the day (with the final meal before 3 p.m.) resulted in significant reductions in blood pressure levels that were “on par with the effectiveness of anti-hypertensive medications.”
On the other hand, those whose eating window was late in the day experienced either no improvement or actually saw an increase in blood pressure. It’s thought that these differences have to do with either aligning eating patterns with the body’s natural circadian rhythms or disrupting them.
“When starting intermittent fasting, it’s advisable to begin gradually and choose an approach that suits your lifestyle,” Ms. Jones said. “Generally, it’s recommended to start with shorter fasting periods, such as the 16/8 method (16 hours of fasting followed by an eight-hour eating window) or the 12/12 method (12 hours of fasting and 12 hours of eating).”
She also advised that people who are fasting consume a balanced diet and stay hydrated. “Pay attention to your body’s signals, and if you experience adverse effects like dizziness or extreme hunger, consider adjusting your fasting schedule.”
