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Keto Diet and Cholesterol: Only the Science

By Liam McAuliffe Updated on — Medically Reviewed and Certified by Dr. Robert Kiltz

Overview

Myths about the keto diet and cholesterol can raise alarms for people. And one of the most persistent, though false alarms is that keto may contribute to unhealthy cholesterol levels. 

These fears stem from the fact that when you eat a low-carb high-fat diet you likely consume more dietary cholesterol than the carb-based standard American diet. The problem is that these fears are based on the misconception that the cholesterol we get from food raises blood cholesterol levels and the risk of heart disease. 

However, numerous high-quality mainstream studies clearly show that there is no evidence that the cholesterol we get from our food increases blood cholesterol levels  [1]After decades of misinformation, this truth can be hard to accept, especially when practicing a ketogenic diet based in high-fat low-carb foods that have been wrongly demonized for their high cholesterol content–foods like red meat, dairy, and eggs. 

In this article we’ll take a closer look at current research on dietary cholesterol, the role it plays in blood cholesterol levels and heart disease, and how a keto diet influences levels of blood cholesterol. 

What is Keto?

Keto is shorthand for the ketogenic diet. It calls for eating few carbohydrates and lots of fat. The name ‘keto’ comes from the metabolic state called ketosis. 

Ketosis occurs when there’s a high concentration of ketones in the blood. Your body creates ketones from the fat you eat and the fat stored on your body when you restrict carbohydrates in your diet.  

Eating in a way that puts the body into ketosis has been around for millennia—in fact, it’s a healthy way humans have evolved to eat.   

If you’re like most people, a ketogenic diet goes against everything you’ve been told about what you should and shouldn’t eat. A typical American diet is about 65% carbohydrates, 15% protein, and 20% fat. Whereas the typical keto diet means you’re eating 70-80% fat, 15-30% protein, and 0-10% carbohydrates. 

When you’ve been told that a salad is the epitome of healthy eating, you probably have a knee-jerk reaction to keto that sounds something like, “Won’t all that fat and cholesterol clog my arteries? 

Probably not, and it’s likely just the opposite is true. Studies show that keto can help you achieve healthier cholesterol levels and other biomarkers associated with heart health. 

What is Cholesterol?

Cholesterol is a type of fat that is absolutely essential for human life. One of the biggest nutritional misconceptions is that eating cholesterol is bad for you [2]. Cholesterol is not only good, it’s vital!

Cholesterol plays many essential roles in your body: 

  • Supports the membranes of every cell
  • Makes important hormones such as estrogen, progesterone, and vitamin D
  • Repairs damaged cells 
  • Protects your intestinal tract
  • Insulates your nervous system
  • Protects against inflammation

Your body makes around 75% of its cholesterol on its own.  You get the other 25% from food like eggs, poultry, dairy, and red meat.2 

The Difference Between Dietary and Blood Cholesterol

Although it may sound like common sense that eating a high-fat low-carb diet filled with cholesterol-rich foods would raise blood cholesterol levels, that’s not the way it actually works. 

Your body expertly regulates your blood cholesterol by controlling how much cholesterol it makes. When you eat more cholesterol, your body makes less. When you eat less cholesterol, your body makes more. 

Because of this regulating ability, studies show that foods high in dietary cholesterol have very little impact on blood cholesterol levels in most people [3] [4] [5] [6]. This is why for most people, high-cholesterol keto foods do not negatively impact your blood cholesterol levels. 

A 2012 study in Nutrition compared a low-calorie diet to a low-carb, high-fat (keto) diet among 360 overweight and obese participants. After one year, participants on the keto diet saw their total cholesterol, triglycerides, and LDL decreased, while HDL rose. HDL is often referred to as “good cholesterol.” 

What is HDL and why is it “Good”?

HDL, or high density lipoprotein, is often called  “good cholesterol.” However, it isn’t actually a type of cholesterol. It’s a lipid-carrying protein that transports cholesterol throughout the body. 

The primary role of HDL is collecting excess cholesterol and transporting it to the liver where it’s recycled or destroyed. This prevents accumulation of cholesterol in the blood, which keeps cholesterol from building up in blood vessels and preventing heart disease. 

HDL particles also have anti-inflammatory and anti-clotting properties. The combination of these beneficial properties is why HDL is associated with cardiovascular health. 

What happens to HDL levels on a keto diet? 

Though eating fat doesn’t affect blood cholesterol levels in a standard carb-heavy diet, when carbs are restricted and fat becomes the basis of your diet, HDL levels ultimately improve. 

So on a keto diet eating fat does affect your cholesterol levels, just in the opposite way we’ve been told! 

Supporting these observations, A 2017 review of human and animal studies found keto diets to be generally associated with reductions in total cholesterol, increases in HDL decreases in triglycerides, and reductions in LDL [7].

A 2020 high quality randomized control study of 34 older adults with obesity found that over 8 weeks participants on the keto diet lost three times the body fat compared with a group eating a low-fat diet. The keto group also had greater improvement in insulin sensitivity, triglyceride levels, and HDL cholesterol [8]

A 2013 meta-analysis of 12 high quality studies involving more than 1200 participants investigating the impact of very-low-carbohydrate ketogenic diets vs. low fat diets, found that the average increase in HDL particles in the low carb group was double that of the low fat group [9]

In 2006, researchers designed a study to look at a more diverse population (other than Caucasian subjects), to understand the effects of carbohydrate restriction on HDL levels in healthy people. Participants were divided into groups of varying levels of carbohydrates. The authors found an increase in HDL amongst all groups, however, the greatest increase was seen in the group consuming the lowest amount of carbohydrates [10]. 

Taken together these findings all affirm that differences in HDL are due to carbohydrate intake, not fat intake.

What is LDL and why is it “Bad”? 

LDL, or low density lipoprotein, is often referred to as “bad cholesterol.” 

The primary role of LDL is to carry cholesterol and triglycerides to cells for energy and to repair the damage. 

Recent science is showing that the most important cholesterol marker is the LDL particle number (LDL-p). This is a measurement of how many LDL particles are floating around in your bloodstream [11] .

Yet most standard blood tests only measure your LDL-c, or how much cholesterol the LDL particles you carry around. It’s important to compare your LDL-p and LDL-c numbers. If LDL-c is high and LDL-p is low then you probably don’t have anything to worry about  [12]

What happens to LDL on Keto Diet? 

A ketogenic diet typically leads to improvements in a range of blood lipids and other markers for cardiovascular health like blood pressure, inflammation, and triglycerides. But the changes to LDL are less predictable and can sometimes go up. 

However, studies show that on keto we typically see that even when the total LDL increases, there is a reduction in the small “bad” LDL, referred to as VLDL or, very low density lipoprotein. This means that most of the increase is in the larger, heart friendlier LDL particles [12].

It’s important to note here that for most people on keto LDL either stays the same or goes down. This finding is reflected in a 2006 study looking at the effects of carbohydrate restriction on LDL cholesterol in a group of 29 men for a 12 week weight-loss intervention found that LDL particle concentrations decreased by 9.6% [13]

What happens to Triglycerides on keto?

Studies show that on a keto diet, triglycerides generally decrease [14]. This makes sense when considering that triglycerides are a type of stored fat. When you’re on keto your body uses fat for fuel leaving less triglycerides to be stored in your fat cells. 

Reduced triglyceride levels decrease the risk of developing chronic diseases including diabetes and cardiovascular disease [15]

Your cholesterol panel on the keto diet

When getting a cholesterol panel on keto there are a few points to consider:

How long have you been on the diet?  It can take some time for your body to adapt to a ketogenic diet, and it will take time for your cholesterol panel to reflect these dietary changes. 

During the first 2-3 months of losing large amounts of weight, which is common on keto,  cholesterol can swing both up and down. Once weight loss stabilizes you’ll get a more accurate read on your levels [16]. 

What were your cholesterol levels prior to switching to a ketogenic diet?  A single value at one point in time won’t give you much information to compare with your keto levels. Serial labs will give you repeat values over time, and this is what you need to make meaningful conclusions

Do you have a genetic condition that may be related to increased cholesterol levels? These conditions include familial hypercholesterolemia, hypothyroidism, as well as chronic inflammation due to autoimmune conditions and lifestyle factors including stress, poor sleep, alcohol use, and smoking. 

What to do if cholesterol worsens on the keto diet?

If your cholesterol worsens on the keto diet, there are adjustments you can make without giving up a low carb lifestyle: 

  • Avoid bulletproof coffee: This refers to adding butter, coconut oil, or MCT oil to your daily cup of coffee.
  • Intermittent fasting: Only eat when hungry. While further research is needed to look at the association between time-restricted eating and cholesterol levels, a recent pilot study of time restricted eating showed a reduction in LDL [17].
  • Reduce saturated fat: Adjust the amount of saturated fat, and balance it with more monounsaturated & polyunsaturated fats. Minimally processed sources are essential. 
  • Incorporate leaner protein sources such as fish, seafood, poultry, and eggs. Dial back the amount of coconut oil, butter, and ghee, and replace these with extra virgin olive oil and avocado oil. 
  • Eat more LDL-lowering keto foods such as low-carb plant foods. These include avocado, dark leafy vegetables, cacao and dark chocolate,  macadamia nuts, brazil nuts, and pecans. One analysis of 25 studies found that eating two servings of nuts per day reduced LDL cholesterol by an average of 7% [18]. However plant foods contain numerous toxins that can harm your body and cause chronic inflammation, so be aware of the trade-off and closely monitor the effects. 
  • Increasing vitamin K2 may help protect heart health by keeping calcium in your bones and out of your arteries. The best sources of vitamin K2 include liver, eggs, grass-fed dairy products, and chicken [19].

The bottom line about cholesterol and the keto diet

Cholesterol is essential to key processes in your body.

Low-carb, high-fat diets such as the ketogenic diet, increase the concentrations of heart-healthy HDL cholesterol when compared against standard high-carb diets. 

Carbohydrate restriction in healthy individuals leads to higher levels of HDL cholesterol. 

Low-carb, high-fat diets generally decrease LDL particle concentration (LDL-P) and increase the size of LDL cholesterol, which is beneficial for cardiovascular health.

Dangerous VLDL cholesterol concentrations in the blood decrease with a ketogenic diet.

Improvement in the total LDL to HDL cholesterol ratio has been demonstrated when dietary carbohydrates are replaced with fat.

When we weigh all the evidence, the benefits of low carb diets on our cholesterol levels greatly outweigh the negatives for most people. 

However, some people may need to adjust their diets in order to meet optimal cholesterol levels. If you have a genetic predisposition, or a history of elevated cholesterol levels or heart issues, please undertake low carb diets with the supervision of your doctor. 

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