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Fasting has been practiced for thousands of years, but only recently have we started to put it to the test. I did a previous video series about the studies on using fasting for weight loss back in the ‘70s. Was it safe? Was it effective? But what about fasting for treating and preventing other diseases?

One of the side effects noticed in the early weight loss studies was a consistent fall in blood pressure––so much so you typically have to stop taking blood pressure medications while fasting, or else your pressures fall too low. Once you start eating again, your pressures go back up, but remarkably, not as high as they were before. But, of course, it depends on what you start eating again.

For example, a case report of a woman who used fasting to drive her rheumatoid arthritis into remission. Systolic blood pressure started up around 170, despite multiple blood pressure medications; was put on a whole-food, plant-based diet for eight weeks. That dropped her down from 170 down to 130––off of all medications before starting the fast, and then normalizing down to 110 after the fast. But is that just because of all the weight loss? She lost 22 pounds on the fast, and 27 pounds on the plant-based diet. So yeah, it’s extraordinary to drop your blood pressure from 170 to 110, but that was after losing about 50 pounds.

We’ve known for decades that any kind of weight loss can lower blood pressure. Even minor weight loss can lower blood pressures in obese persons, even if they remain significantly overweight. But most of the drop in blood pressures with severe caloric restriction happens within the first two days, before significant loss of body fat. So, it may also be a reduction in the fight-or-flight stress hormones, like adrenaline and noradrenaline, both before…and after exercise, after just two weeks of just a few hundred calories a day.

So, that may be one reason why very low-calorie diets have been found useful in lowering blood pressures, even in those for whom blood pressure medications fail: the changes in those hormones. But, low-calorie diets also tend to be more plant-based. So, there’s fiber and potassium-rich foods, less saturated fat. Even just adding fruits and vegetables to the diets of hypertensives can lower their systolic blood pressure—the top number—by seven points. That’s the kind of blood pressure improvement you might get from losing 10 pounds, just by eating more fruits and vegetables. And, if you combine that with a drop in meat consumption, not only doubling fruit and vegetable intake, but combining that with trying to slash saturated fat and cholesterol, you can cut pressures by 11 points.

What else can we do? Restricting alcohol intake in regular daily drinkers can drop you five points. So, let’s keep track here: alcohol restriction can drop your systolic blood pressure five points, losing ten pounds can drop you seven, as can just eating the recommended eight to 10 servings of fruits and vegetables a day. Regular aerobic exercise for at least three months can drop you nine…. So, let’s add that on to the chart. Combine the fruits and vegetables with meat reduction, and you can drop it 11. Blood pressure medications can have side effects, but on their own, can drop pressures by 15 points.

What about cutting down on salt? Note in the other diet study they kept the sodium levels the same. Cut sodium enough, and it can edge out drugs at 16: the drugs 15, sodium restriction 16. Is that the best we can do with diet? Put people on a purely plant-based diet, even one moderate in sodium, and you can drop hypertensives by 18 points, even after nine out of 10 reduced their blood pressure medications or stopped them entirely, all within just seven days. That’s pretty impressive. Now, what if you took that same diet, but added fasting? 37 points! We’ll review that study and others like it, next.

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