Cholesterol and
low-carb diets

By , medical review by , Evidence based
Cholesterol is an essential component of our bodies and, although there are clear data showing an association between having high blood cholesterol levels and increased cardiovascular risk, it is not clear that high cholesterol equates with increased cardiovascular risk for everyone.
 
Read on to learn what cholesterol is, how your body uses it, why low-carb and keto diets may lead to a change in blood cholesterol levels, and whether you should be concerned if your cholesterol increases with a keto or low-carb lifestyle.

Disclaimer: The negative effects of high serum cholesterol levels on human health are well established in the medical literature. However, we acknowledge that gaps exist in the scientific literature which do not include specific populations, such as in the context of a low-carb diet.

This guide is our attempt at summarizing what is known. It is written for adults who are concerned about cholesterol and health, especially when eating a low-carb diet. Discuss any lifestyle changes with your doctor. Full disclaimer

For even more details and relevant research on connected topics, see our guides to healthy fats, vegetable oils and saturated fats. Also see our list of core scientific studies related to heart disease, cholesterol and saturated fats.

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The basics: What is cholesterol?

Cholesterol is a waxy substance that is essential for the life of all animals, including humans.

Cholesterol is found in virtually every cell of your body and is necessary for many bodily functions, including:

  • Cell integrity: As an integral part of every cell membrane in the body, cholesterol is required for maintaining cell structure and fluidity.
  • Hormone synthesis: Cholesterol is needed to make steroid hormones such as estrogen, testosterone, cortisol, and other related hormones, such as vitamin D3.
  • Creation of bile acids: Your liver converts cholesterol into bile acids, which help you absorb fats and the essential fat-soluble vitamins A, D, E and K.
  • Myelin formation: The myelin sheath that surrounds and protects nerve cells contains plenty of cholesterol.

 
Your body makes most of the cholesterol that is found in your bloodstream. It’s primarily produced in the liver.

Dietary cholesterol – found in animal foods like eggs, shellfish, cheese, and organ meat – makes up a smaller portion of your blood cholesterol pool.

Unlike fat, which contains nine calories per gram, cholesterol has no calories. Because it’s present in foods in very small amounts, it’s measured in milligrams instead of grams. Most fatty meats and whole-milk dairy products contain just a little cholesterol, whereas some shellfish and organ meats are high in cholesterol, yet low in fat.

After years of advice to toss the egg yolks and eat only the whites, we’ve learned that eating cholesterol-rich foods doesn’t impact blood cholesterol levels very much. In fact, when people take in more cholesterol from food, the liver usually produces less, resulting in stable blood cholesterol.

You can learn more about cholesterol, including the specific types of lipids and lipoproteins, in our evidence-based guide: What is cholesterol?


 

How does keto or low-carb eating affect your cholesterol?

For most people, there will be no adverse effects on blood levels of lipids when consuming a ketogenic diet. Typical findings are stable LDL cholesterol levels, a decrease in triglycerides (good), and an increased HDL cholesterol (also good). Some people will even see a drop in their LDL.

In some people, a keto or low-carb diet will result in an increase in both LDL and HDL cholesterol levels.

Or, there is an increase only in HDL cholesterol resulting in an improved LDL/HDL ratio.

One meta-analysis of randomized trials reported that people eating a low-carb diet, on average, experience a reduction in both total LDL and small LDL particles, as well as an increase in the peak LDL size.

However, for an estimated 5 to 25% of people – whether weight loss occurs or not – LDL cholesterol goes up significantly in response to very-low-carb diets, sometimes by 200% or more.

The exact mechanism for the rise in LDL is still a matter of debate, as is the clinical significance.

Please see our dedicated guide about low-carb LDL hyper-responders for more information.

 


 

Should you be concerned if your cholesterol increases with low-carb eating?

This is an emerging area of research that is currently the focus of a great deal of debate and uncertainty.

Traditionally, experts in the field of lipids and heart disease have viewed elevated LDL cholesterol with concern because it typically reflects a high concentration of LDL particles (LDL-P) circulating in the bloodstream.

Excessive amounts of LDL particles have been found to be associated with the development of atherosclerosis, the underlying cause of heart disease.

Despite the associations between high concentrations of LDL particles and heart disease, research has consistently shown that keto diets help reduce many heart disease risk factors in people with diabetes and other insulin-resistant conditions.

Granted, trials showing an actual reduction in heart attacks don’t yet exist. Will the demonstrated improvement in risk factors result in a net beneficial effect despite increased LDL? That is unknown, but some evidence suggests that it may be the case.

The fact that so many risk factors remain stable or improve with carb restriction – even if LDL cholesterol levels increase – demonstrates the importance of not viewing any one value in isolation. Instead, it may be better to look at the body as a whole system.

However, some experts urge caution. Prominent lipidologist and vocal lipid educator Dr. Thomas Dayspring states:

“The advocates of low-carb diets say there is no study showing harm of elevated LDL-P and LDL-C in patients who have eliminated or drastically reduced their insulin resistance and inflammatory markers by low carbing. That is true, but what they want to ignore is that there is no data anywhere that shows they are an exception.”

Time will tell if data support one position or the other. For now, if you want to learn more about the risk of LDL, please see our evidence-based guide: Is elevated LDL cholesterol harmful?


 

Five ways to lower your LDL on a keto or low-carb diet

Has your cholesterol increased on a low-carb diet? Do you fear that you may need to abandon this way of eating and its potential benefits?

Here are five ways you can reduce your total and LDL cholesterol levels while maintaining a keto or low-carb lifestyle. Consider trying them in this order, and take a look at our more detailed guide: How to lower LDL cholesterol on a low-carb diet.

1. Avoid adding fat to your coffee

Bulletproof coffee refers to adding butter, coconut fat, or MCT oil to coffee. Avoid drinking significant amounts of fat when you’re not hungry. This alone can sometimes normalize elevated cholesterol levels.

2. Eat only when hungry

Only eat when hungry and consider adding intermittent fasting. This may reduce cholesterol levels. Although most research on intermittent fasting and LDL reduction comes from low-quality observational studies during Ramadan, a recent pilot study of time restricted eating showed a significant reduction in LDL.

While we need more data, this remains a promising intervention.

3. Eat foods higher in unsaturated fats instead of saturated fats

Foods higher in unsaturated fats include fats like olive oil, fatty fish and avocados. Replacing sources of saturated fat with these foods may be enough to lower LDL cholesterol.

However, remember that many unsaturated oils are highly processed. As with food, we recommend focusing on the least processed oils like olive oil, macadamia oil, and avocado oil.

4. Eat LDL-lowering keto-friendly foods

These low-carb plant foods may help lower cholesterol levels somewhat:

Starch structure

  • Avocado: An analysis of 10 studies found that eating avocados on a regular basis led to a significant decrease in LDL cholesterol.
  • Green vegetables: Dark leafy greens and cruciferous vegetables bind to bile acids, which are excreted as waste rather than reabsorbed in the gut, ultimately resulting in slightly lower blood cholesterol. To maximize this effect, you may want to steam your greens rather than eating them raw.
  • Cocoa and dark chocolate: In addition to lowering LDL cholesterol, cocoa and dark chocolate might help protect LDL from becoming oxidized or damaged.
    To avoid unnecessary sugar intake, you may want to choose chocolate that contains at least 85% cocoa.
  • Nuts and seeds: Nuts and seeds are rich in fiber and monounsaturated fats, which can help lower cholesterol. One analysis of 25 studies found that eating two servings of nuts per day reduced LDL cholesterol by an average of 7%.

5. Eat more carbs

Finally, if steps 1-4 are not enough: Consider whether you really need to be on a strict keto diet for health reasons.

If a more moderate or liberal low-carb diet (e.g. 50–100 grams of carbs per day) can still work for you, it may also lower your cholesterol. Just remember to choose unprocessed carb sources (e.g., not wheat flour or refined sugar).


 

Recommended viewing and reading

Videos

Dave Feldman: The cholesterol network system
 
Dr. Andrew Mente: Dietary fat and cardiovascular disease
 
Sarah Hallberg: LDL on LCHF
 
Dr. Peter Attia: The straight dope on cholesterol

Articles

Dr. Peter Attia: The straight dope on cholesterol (part 1 of 9)

Dr. Thomas Dayspring: Understanding the entire lipid profile

Cholesterol Code: Are you a lean mass hyper-responder?

/ Franziska Spritzler, RD

 

Franziska Spritsler - Q&A - Still 3
All articles and guides by Franziska Spritzler

Franziska Spritzler is a registered dietitian, author and certified diabetes educator who takes a low-carb, real-food approach to diabetes, weight management and overall health.

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