Keto Diet: Cholesterol Friend Or Foe?

The ketogenic diet is a high-fat, low-carb, moderate-protein diet that promotes the use of fat as a fuel source instead of carbohydrates. While it is known to have several health benefits, its impact on cholesterol levels is still being studied.

Some studies have shown that a ketogenic diet can lead to an increase in LDL (bad) cholesterol levels, especially in individuals with certain medical or genetic conditions. However, other studies have found that a ketogenic diet can increase HDL (good) cholesterol levels and decrease triglyceride levels, which are beneficial for heart health.

The impact of a ketogenic diet on cholesterol levels may vary depending on individual factors such as weight loss, thyroid function, inflammation, and stress levels. It is recommended to consult a doctor and get blood tests to monitor cholesterol levels when starting a ketogenic diet.

Overall, while the ketogenic diet may have benefits for some individuals, it is important to be cautious, especially for those with high cholesterol or certain medical conditions. Adjustments can be made to the diet, such as reducing saturated fat intake and increasing monounsaturated and polyunsaturated fat intake, to optimize cholesterol levels.

The impact of keto on HDL cholesterol

The ketogenic diet is a high-fat, moderate-protein, and very low-carbohydrate diet. It is popular for its weight-loss benefits, but some worry about its impact on cholesterol levels.

Cholesterol is a waxy substance that is essential for the life of all animals, including humans. It is found in virtually every cell of your body and is necessary for maintaining cell structure and fluidity, hormone synthesis, creating bile acids, and forming the myelin sheath that surrounds and protects nerve cells.

There are several types of lipoproteins that carry cholesterol in the bloodstream, but the two most common are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL is known as "bad cholesterol" because higher levels are correlated with higher heart disease risk, while HDL is known as "good cholesterol" because higher levels are correlated with lower heart disease risk.

The impact of the keto diet on HDL cholesterol is not straightforward. Some studies suggest that the keto diet can lower HDL levels, while others suggest it can raise them.

A 2004 study found that a 24-week ketogenic diet in obese patients resulted in a significant increase in HDL cholesterol levels. Another study of 66 obese people with high or normal cholesterol found that after 56 weeks of a keto diet, participants had lower LDL and higher HDL. Similarly, a meta-analysis of studies in overweight or obese people with or without type 2 diabetes found that keto raised HDL levels.

On the other hand, some studies have found that the keto diet can lower HDL levels. A 2019 study found that participants who followed the keto diet for six months had higher HDL cholesterol levels than those following a low-fat diet, but in a follow-up study, the researchers found conflicting results. Some participants who followed the keto diet for two months experienced a rise in LDL cholesterol levels, while others showed a decrease after six months.

Factors Affecting the Impact of Keto on HDL Cholesterol

The impact of the keto diet on HDL cholesterol may depend on various factors, including the quality of the diet, individual genetics, and body composition.

The quality of the keto diet is important. If the diet includes unhealthy choices such as butter, coconut oil, and animal fat, which are sources of saturated fat, it may negatively impact HDL levels. On the other hand, if the diet includes heart-healthy, low-carb foods such as unsaturated fats like olive oil, avocado, and nuts, it may have a positive impact on HDL levels.

Individual genetics also play a role in cholesterol levels. For example, those with a genetic condition called familial hypercholesterolemia tend to have very high cholesterol levels and a high risk of heart disease.

Body composition, particularly obesity and diabetes, can also affect the impact of the keto diet on HDL cholesterol. In obese people and those with diabetes, keto generally improves heart disease risk factors like LDL, HDL, triglycerides, and blood pressure.

While the research on the impact of the keto diet on HDL cholesterol is mixed, it appears that the quality of the diet, individual genetics, and body composition may play a role in determining its effects. More long-term studies are needed to fully understand the true effects of keto on HDL cholesterol.

The impact of keto on LDL cholesterol

The ketogenic diet is a high-fat, low-carbohydrate diet that has gained popularity as a weight-loss tool and for its potential benefits in managing certain health conditions. While the keto diet has been associated with improvements in various health markers, its impact on cholesterol levels, particularly LDL (low-density lipoprotein) cholesterol, is more complex and varies across individuals.

LDL Cholesterol and Cardiovascular Risk

LDL cholesterol is often referred to as the "bad" cholesterol because high levels are associated with an increased risk of heart disease. LDL particles can accumulate in the walls of arteries, leading to the development of atherosclerosis, which is the underlying cause of heart disease. Therefore, maintaining healthy LDL levels is crucial for cardiovascular health.

The keto diet's high-fat content, including saturated fats, can influence LDL cholesterol levels. The majority of people following a ketogenic diet may experience a mild increase, stable levels, or even a decrease in LDL cholesterol. However, a subset of individuals, referred to as "hyper-responders" or "lean mass hyper-responders," can exhibit a more dramatic elevation in LDL cholesterol levels.

In a case series by Schmidt et al. (2023), 17 patients who consumed a ketogenic diet and were referred to cardiology for high cholesterol were evaluated. The average baseline LDL cholesterol was 129 mg/dL, and after an average of 12.3 months on the keto diet, the average LDL level increased to 316 mg/dL, representing a 245% increase. This substantial rise in LDL cholesterol highlights the potential impact of the keto diet on certain individuals.

It is important to note that the exact mechanism behind the rise in LDL cholesterol among hyper-responders is still a subject of ongoing research. One hypothesis suggests that these individuals may consume a higher ratio of saturated to unsaturated fatty acids compared to others on the ketogenic diet. Additionally, underlying genetic factors may play a role, as some hyper-responders have been found to carry mutations in the LDL-R gene, which is associated with elevated LDL cholesterol levels.

Managing LDL Cholesterol on Keto

For individuals who experience elevated LDL cholesterol while on a ketogenic diet, there are several strategies that may help manage their levels:

• Avoid adding excessive amounts of fat to your diet, especially when not hungry.
• Consume unsaturated fats, such as olive oil, fatty fish, and avocados, instead of saturated fats.
• Include LDL-lowering keto-friendly foods like avocados, green vegetables, cocoa, dark chocolate, nuts, and seeds.
• Consider intermittent fasting or time-restricted eating, which may help reduce LDL levels.
• If necessary, adjust your carbohydrate intake by adding small servings of healthier starches or adopting a more moderate low-carb diet.

While the ketogenic diet can be beneficial for weight loss and certain health conditions, its impact on LDL cholesterol levels varies. Most individuals may experience stable or mildly increased LDL levels, but a subset of "hyper-responders" can exhibit dramatic elevations. Further research is needed to fully understand the mechanisms behind these variations and the long-term clinical implications. For individuals experiencing high LDL cholesterol on keto, dietary adjustments and medical guidance are recommended to manage their cholesterol levels effectively.

The impact of keto on triglycerides

Triglycerides are among the most predictable changes when one adapts to and maintains a well-formulated ketogenic diet. For people starting with elevated triglycerides, they almost always show a sharp and sustained reduction. On average, people with metabolic syndrome will see their serum triglycerides reduced by half when on a ketogenic diet.

In a study of 83 obese patients, triglyceride levels decreased significantly following 24 weeks of treatment. Similarly, a study of 360 overweight and obese participants found that after about a year, those in the keto group saw their triglyceride levels decrease.

However, there are people who may not respond this way, and the exceptions tend to be people whose serum triglycerides were already within the abnormal range. Increases in triglycerides during a well-formulated ketogenic diet may occur, but this is rare. In those cases, it may be due to carbohydrate consumption that is greater than one's tolerance or due to alcohol consumption in the day or two prior to the blood test.

The impact of keto on total cholesterol

The ketogenic diet is a high-fat, low-carb, and moderate-protein diet. It typically provides only 5-10% of calories from carbohydrates (20-50g/day), 10% of calories from protein, and 70-80% of calories from fat. While the diet is high in fat, it does not increase "bad" cholesterol levels and clog your arteries. In fact, recent research shows that high-fat, low-carb diets can optimise your cholesterol levels and improve your heart health.

The Different Types of Cholesterol

Cholesterol is a waxy substance that is essential for the life of all animals, including humans. It is found in virtually every cell of your body and is necessary for many bodily functions, including cell integrity, hormone synthesis, and the creation of bile acids. There are two important classes of lipids in the body: triglycerides and cholesterol.

Triglycerides are fatty acids that store energy for later use. They can be broken down into other fatty acids and glycerol, which can be converted into glucose. Elevated levels of triglycerides in your blood can increase your risk of developing diabetes, cardiovascular illnesses, and other life-threatening diseases.

Cholesterol, on the other hand, is produced by the body in the liver and other cells, and is also obtained from consuming animal-based foods. It is transported in the blood by molecules called lipoproteins, which come in five forms: chylomicrons, very-low-density lipoproteins (VLDL), intermediate-density lipoproteins (IDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL).

The Impact of Keto on Cholesterol Levels

The ketogenic diet has been shown to have a positive impact on cholesterol levels. Firstly, it increases the concentrations of HDL cholesterol, also known as the "good" cholesterol, more than low-fat, high-carb diets. HDL cholesterol helps to prevent cholesterol from accumulating and clogging arteries, thus reducing the risk of cardiovascular diseases.

Secondly, the ketogenic diet decreases LDL particle concentration (LDL-P) and increases the size of LDL cholesterol. LDL is often referred to as the "bad" cholesterol, as increased levels are associated with a higher risk of cardiovascular diseases. However, it is important to note that the size of LDL particles matters; larger LDL particles are considered healthier, while smaller, dense LDL is more harmful.

Finally, the ketogenic diet decreases the amount of harmful VLDL cholesterol in the blood. VLDL particles are the main transporters of triglycerides in the body and are more likely than other lipoproteins to clog vessels and impair vascular functions.

The Role of Specific Fatty Acids

The ketogenic diet optimises cholesterol levels by replacing carbohydrates with fats that reduce the total-to-HDL cholesterol ratio. These include stearic acid, found in high quantities in animal fats, and lauric acid, found in coconut oil. Unsaturated fats, especially polyunsaturated fats, also decrease the ratio.

Monitoring Cholesterol Levels on Keto

While the ketogenic diet has beneficial effects on cholesterol levels for most people, there is a small subset of individuals who experience an increase in total cholesterol and LDL cholesterol. This may be related to genetic factors or conditions such as familial hypercholesterolemia, hypothyroid issues, or chronic inflammation and stress.

If you are concerned about your cholesterol levels while on the ketogenic diet, it is important to consult your doctor and get your blood tested. The total-to-HDL cholesterol ratio is a good predictor of cardiovascular disease risk and should ideally be between 3 and 4.

Adjustments to Optimise Cholesterol Levels on Keto

If you find that your cholesterol levels are worsening on a standard ketogenic diet, you can make some adjustments to improve heart health. Replace most of your saturated fat intake with minimally processed sources of monounsaturated and polyunsaturated fats. This includes foods such as extra virgin olive oil, avocado oil, nuts, seeds, avocados, and fatty fish.

In conclusion, the ketogenic diet has been shown to have a clinically positive impact on cholesterol levels for most people. It increases HDL cholesterol, decreases LDL particle concentration and size, and reduces harmful VLDL cholesterol. However, a small subset of individuals may experience an increase in total cholesterol and LDL cholesterol, and adjustments to their diet may be necessary.

What to do if keto raises your cholesterol

Interpreting cholesterol numbers

Interpreting cholesterol numbers can be complicated. Most people are familiar with Total, HDL and LDL cholesterol. People with high HDL (the "good") have a low risk of heart disease, while people with high LDL (the "bad") have an increased risk. However, the true picture is more complicated than "good" or "bad". The "bad" LDL has subtypes, primarily based on the size of the particles. People who have mostly small LDL particles have a high risk of heart disease, while those with mostly large particles have a low risk.

The most important marker of all is the LDL particle number (LDL-p), which measures how many LDL particles are floating around in your bloodstream. This number is different from LDL concentration (LDL-c), which measures how much cholesterol your LDL particles are carrying around. This is what is most commonly measured on standard blood tests.

If your LDL cholesterol is high, but your LDL particle number is normal (called discordance), then you probably have nothing to worry about.

What to do if your cholesterol levels are high

If you are on a low-carb ketogenic diet and your cholesterol levels are high, there are several things you can do:

• Have your doctor measure your LDL-p (LDL particle number)… or ApoB, which is another way of measuring LDL particle number.
• Remove "Bulletproof" coffee from your diet. This involves adding 1-2 tablespoons of MCT oil or coconut oil and 2 tablespoons of butter to your morning cup of coffee.
• Replace some saturated fats with monounsaturated fats. Cook with olive oil instead of butter and coconut oil. Eat more nuts and avocados.
• Eat more fibre-rich, real-food carbs. Try eating 1-2 pieces of fruit per day or small servings of healthier starches like rice and oats.
• Eat LDL-lowering keto-friendly foods. These low-carb plant foods may help lower cholesterol levels: avocado, green vegetables, cocoa and dark chocolate, and nuts and seeds.
• Exercise, get better sleep and minimise stress levels.

When to seek medical advice

If you have high cholesterol levels and are interested in trying the keto diet, it’s important to ask a healthcare professional whether the diet is suitable for you, based on your particular cholesterol levels and overall health.

When to avoid keto

The keto diet is likely not the best option for you if you have kidney disease, liver diseases, familial hypercholesterolemia (high cholesterol levels inherited from family), or fat-induced lipemia, because the diet may worsen these conditions.

Frequently asked questions