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Quick Summary tl;dr
Low-density-lipoprotein" (LDL) is often referred to as "bad cholesterol." This is incorrect for two reasons. First, LDL is not cholesterol but a cholesterol carrier particle. Second, there are different types of LDL. In general, big LDL is good and only smaller LDL is bad (causes heart disease).
It’s the combined presence of high LDL and sugar (from carbohydrate-rich diets) that causes LDL to shrink and increases the risk for heart disease.
If your LDL increases on a high-fat, low-carbohydrate ketogenic diet, it’s likely primarily because your liver is shipping out more LDL particles to carry fat fuel to your organs. Cholesterol comes along for the ride.
LDL may not have the same impact on cardiovascular risk when you’re eating low-carb.
Analogy #1 – Boats in Your Bloodstream
"Low-density-lipoprotein" (LDL) is like a boat that transports two types of cargo through the bloodstream. LDL transports cholesterol (an essential cellular building block for cell membranes and hormones) and triglycerides (fat fuel) from the liver to organs around the body that need building blocks and fuel.
LDL Levels Can Increase for Two Reasons
If you’re eating a low-carb diet and burning fat as fuel, your liver sends out more LDL boats to supply fat fuel to your muscles. The empty LDL boats return to the liver to dock, restock, and go back to work.
Alternatively, when you overeat carbs, it is as if you’re filling your bloodstream with sugar glaciers. The LDL boats bump into these sugar glaciers and get damaged in a process classed glycation. (Glycation, in turn, makes those LDL boats further vulnerable to another damaging chemical process called oxidation.) Once damaged by the sugar glaciers, the LDL boats can’t return to the liver and end accumulating in your bloodstream. Eventually, they shrink down and sink down to your artery walls and develop atherosclerotic plaques, a titanic health catastrophe.
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Therefore, the perception that LDL is "bad" is not entirely true. More LDL may be needed when you’re burning lots of fat fuel. In fact, the kind of big fluffy LDL that sometimes increases on a low-carb diet is actually cardioprotective! ( 1, 2, 3) By contrast, LDL is bad when it gets damaged by carbs and oxidation, causing it to sink and leading to heart disease ( 1, 2, 4, 5).
Then, there is "high-density lipoprotein" (HDL). Often called "good" cholesterol (although neither LDL nor HDL are themselves cholesterol), HDL is like a rescue submarine that salvages cargo from sinking LDL, cleaning up your bloodstream and protecting against heart disease ( 6).
The perception that LDL is "bad" is not entirely true. More LDL may be needed when you’re burning lots of fat fuel. LDL is bad when it gets damaged by carbs and oxidation, causing it to sink and leading to heart disease.
Analogy #2 – Star Wars
LDL has been labeled "bad cholesterol," but that’s not strictly speaking true for two reasons. First, LDL, which stands for "Low Density Lipoprotein," is not actually cholesterol itself but a package of particles that includes cholesterol as well as fats called triglycerides that your cells use for energy. LDL is made by the liver to carry cholesterol and triglycerides to organs that need them.
LDL is a good guy.
In our Star Wars analogy, LDL is Anakin Skywalker. But, as you well know (I hope), Anakin is corrupted by the real bad guy, Darth Lord Sidious. In the blood, the Lord Sidious is sugar. Sugar from our diets corrupts LDL by binding to it in a process called "glycation," which causes it to "oxidize," or turn to the Dark Side. Thus, rises small dense LDL Vader!
It’s small dense LDL, and specifically small dense and oxidized LDL, that is dangerous for the hearts. So, while you should fear Vader, it’s not really his fault. The real enemy is the Darth Lord Sugar.
Not all LDL cholesterol is bad. It’s small dense LDL, and specifically small dense and oxidized LDL, that is dangerous for the hearts.
For more science-backed articles related to this topic, read the posts below:
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Trialed and Tested Recipes
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