There is a window of time when adequate physical activity can help offset some of the damage caused by eating unhealthy foods.
I’ve previously discussed studies that show a single diet high in saturated fat can impair vascular function in men, as measured in the arm, but that’s about blood flow to the heart wall. The researchers chose the men to eat a high-fat diet that was more than 60% fat, half saturated, with more than zero cholesterol, or a low-fat diet that was carbs, less than 10% fat, and 50 times less cholesterol.
Below again at 0:47 in my video Exercise to Protect Your Arteries from Fast Foodyou can see a Doppler recording of the left anterior descending coronary artery, known as the widow maker, before a high-fat meal (top). Its good strong signal was squeezed a few hours after eating; the photo (below) was taken five hours after a high-fat meal.
Coronary flow reserve decreases after a high-fat meal, but not after a low-fat meal with the same amount of calories.
What does “coronary reserve” mean? When part of the coronary artery is blocked for any reason, the surrounding vessels expand. That extra capacity for expansion is called i coronary flow reserveand is tied up within a few hours after eating a fatty meal, making the heart unable to compensate for clogged arteries. That’s how a high-fat diet affects blood flow to the heart.
In extreme cases, you can even witness behind the other person’s eye. Below are before and after photos of the retina, which you can also see at 1:34 in mine. video.
The first image shows milky blood vessels, and the second shows what happens after eating a low-fat diet and drugs help remove fat from the blood. Do you see the difference? In the first picture, the blood looked like a milkshake.
What happens if you exercise right after eating that high-fat meal? Postprandial inflammation following increased levels of fat in the blood after a high-fat meal is a possible explanation for the increased risk of cardiovascular disease, but much evidence shows that vigorous exercise is an effective way to get rid of some of that fat after a meal. However, the beneficial effects of vigorous exercise on postprandial lipemia appear to be relatively short-lived. Going a few days without exercise can completely negate any benefit, no matter how strong you are. The time window seems to be between 18 hours before a meal and about 90 minutes after a meal. And how much exercise do we need? About an hour of moderate exercise should do it.
In one study, it took only 20 minutes to climb the stairs, divided into five-minute intervals every hour for four hours after a McDonald’s breakfast of hash browns, eggs, pancakes, an English muffin, sausage, and a milkshake. After such a meal, blood vessel function decreased significantly when people just sat down after eating, but not when they did an hour-long stair-climbing exercise. Therefore, exercising every hour may reduce the negative effects of not only sitting for a long time but also eating a high-fat diet, “suggesting that climbing stairs should be included as an accessible way of life to protect blood vessels. [artery] work.” Of course, it goes without saying the rest The way you can protect artery function is to not eat breakfast at McDonald’s in the first place.
Such food can also have more than 2,000 mg of sodium. That’s more than the 1,500 mg the American Heart Association recommends we stay under for a day. Give a person a low-salt meal, even a third less, and that alone can still impair vascular function within an hour of consuming it, even without an increase in blood pressure.
When it comes to blood pressure, some people are “salt insensitive,” meaning they suffer from a large spike in blood pressure when they eat salt, but others are “salt intolerant.” Their blood pressure is less dependent on their salt intake. So, is salt good for these people? No. A high sodium diet reduces arterial pressure regardless of whether your blood pressure is salt-sensitive or salt-insensitive. Your artery function is impaired in any way, from a low-salt diet to a high-salt diet, which you can see below and at 3:53 in my video.
There is an influence of dietary salt on blood pressure. Despite the “seeming consensus,” some researchers (often heavily funded by the salt industry) say it’s actually not good to cut back on salt, but the evidence is against these naysayers. Like saturated fat in meat, milk, and produce, science shows that sodium—not sodium reduction—is the “real culprit.”
Doctor’s Note
This is the second in a three-part series on saturated fat and cardiovascular health. The first was How One Diet Can Damage Your Arteries and Lungs. Next is Protect Your Arteries From Full Breasts With These Foods.
Still not sold on the dangers of salt? See Evidence That Salt Raises Blood Pressure.
