Harvard Medical School, in a study led by J. Michael Gaziano, looked at various predictors for heart disease and found that the ratio of triglycerides to HDL was a better predictor for heart disease than anything else, including cholesterol levels. They divided the subjects into four groups according to their ratio of triglycerides to HDL and found that those with the highest ratio (i.e., high triglycerides to low HDL) had a sixteen times greater risk of heart attack than those with the lowest ratio (low triglycerides to high HDL). 12
There’s more. Most of us are familiar with “good” cholesterol (HDL) and “bad” cholesterol (LDL), but what is not as well known is that both types of cholesterol have sub-parts that behave very differently from one another. What kind of LDL you have turns out to be much more important than just the amount of LDL you have (an LDL-gradient-gel electrophoresis test is now widely available to tell you about your LDL). For example, LDL cholesterol comes in two basic flavors: it can be a big, fluffy, cotton ball–like molecule (LDL-A type), or it can be more like a dense, tight BB-gun pellet (LDL-B type). The big, fluffy LDL-As are pretty harmless. They are far less likely to become oxidized or damaged and cause problems. But the little LDL-Bs are a different story. Those are the ones that cause problems, and those are the ones you should be concerned about. The Gaziano study found that high triglycerides correlate strongly with high levels of the dangerous LDL-B particles, and low levels of triglycerides correlate with higher levels of the harmless LDL-As. In other words, the higher your triglycerides, the greater the chance that your LDL cholesterol is made up of the B-particles (the kind that is way more likely to lead to heart disease). The take-home point: reduce your triglycerides (and raise your HDL), and you reduce your risk of heart disease.
Insulin and Hypertension
As you saw in the previous paragraphs on heart disease, high levels of insulin can narrow the arterial walls which, in turn, will raise blood pressure, since a more forceful pumping action is required to get the blood through the narrower passageways. But there’s an even more insidious way in which insulin raises blood pressure.
It talks to the kidneys.
Insulin’s message to the kidneys is this: hold on to salt . Insulin makes the kidneys do this even if the kidneys would much prefer not to. Since sodium, like sugar, is controlled by the body within a very tight range, the kidneys figure, “Listen, if we have to hold on to all this salt, we’d better bring on more water to dilute it so that it stays in the safe range.” And that’s exactly what they do. Increased sodium retention results in increased water retention. More fluid means more blood volume, and more blood volume means higher blood pressure. Fully 50% of people with hypertension have insulin resistance. 13
Insulin will also ultimately raise adrenaline, and adrenaline will raise both blood pressure and heart rate. We’ll discuss the insulin–adrenaline axis a little more, under the topic of obesity in the next section.
How Does a Low-Carb Diet Lower Your Risk of Hypertension?
Lowering insulin levels will intercept the message to the kidneys to hold on to salt. You will almost immediately lose water weight, and bloat and blood pressure will go down. Lowering insulin is actually such an effective strategy for lowering blood pressure that it sometimes works too well too fast. In rare cases, your blood pressure might dip too low, and you may experience lightheadedness or dizziness upon standing up. This is why some clinicians recommend increasing salty foods or adding a teaspoon of salt to your food on a daily basis if you find this happening to you. 14
When the kidneys dump excess sodium, potassium sometimes gets caught in the crossfire and you wind up dumping potassium as well. This is even truer if you exercise and sweat a lot. You don’t want
There’s more. Most of us are familiar with “good” cholesterol (HDL) and “bad” cholesterol (LDL), but what is not as well known is that both types of cholesterol have sub-parts that behave very differently from one another. What kind of LDL you have turns out to be much more important than just the amount of LDL you have (an LDL-gradient-gel electrophoresis test is now widely available to tell you about your LDL). For example, LDL cholesterol comes in two basic flavors: it can be a big, fluffy, cotton ball–like molecule (LDL-A type), or it can be more like a dense, tight BB-gun pellet (LDL-B type). The big, fluffy LDL-As are pretty harmless. They are far less likely to become oxidized or damaged and cause problems. But the little LDL-Bs are a different story. Those are the ones that cause problems, and those are the ones you should be concerned about. The Gaziano study found that high triglycerides correlate strongly with high levels of the dangerous LDL-B particles, and low levels of triglycerides correlate with higher levels of the harmless LDL-As. In other words, the higher your triglycerides, the greater the chance that your LDL cholesterol is made up of the B-particles (the kind that is way more likely to lead to heart disease). The take-home point: reduce your triglycerides (and raise your HDL), and you reduce your risk of heart disease.
Insulin and Hypertension
As you saw in the previous paragraphs on heart disease, high levels of insulin can narrow the arterial walls which, in turn, will raise blood pressure, since a more forceful pumping action is required to get the blood through the narrower passageways. But there’s an even more insidious way in which insulin raises blood pressure.
It talks to the kidneys.
Insulin’s message to the kidneys is this: hold on to salt . Insulin makes the kidneys do this even if the kidneys would much prefer not to. Since sodium, like sugar, is controlled by the body within a very tight range, the kidneys figure, “Listen, if we have to hold on to all this salt, we’d better bring on more water to dilute it so that it stays in the safe range.” And that’s exactly what they do. Increased sodium retention results in increased water retention. More fluid means more blood volume, and more blood volume means higher blood pressure. Fully 50% of people with hypertension have insulin resistance. 13
Insulin will also ultimately raise adrenaline, and adrenaline will raise both blood pressure and heart rate. We’ll discuss the insulin–adrenaline axis a little more, under the topic of obesity in the next section.
How Does a Low-Carb Diet Lower Your Risk of Hypertension?
Lowering insulin levels will intercept the message to the kidneys to hold on to salt. You will almost immediately lose water weight, and bloat and blood pressure will go down. Lowering insulin is actually such an effective strategy for lowering blood pressure that it sometimes works too well too fast. In rare cases, your blood pressure might dip too low, and you may experience lightheadedness or dizziness upon standing up. This is why some clinicians recommend increasing salty foods or adding a teaspoon of salt to your food on a daily basis if you find this happening to you. 14
When the kidneys dump excess sodium, potassium sometimes gets caught in the crossfire and you wind up dumping potassium as well. This is even truer if you exercise and sweat a lot. You don’t want
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