Keto Diet and Cholesterol: Benefits, Risks, Genetics - Verywell Health

The ketogenic, or keto, diet is a popular diet that is very low in carbohydrates and high in fat. It is different from most low-carb diets in that it is much more strict in the number of macronutrients allowed. Macronutrients are carbohydrates, fats, and protein. They provide calories and energy and make up the greatest amount of nutrients people consume.

While there is no one "standard" keto diet with a specific ratio of macronutrients, the keto diet typically limits total carbohydrate intake to only about 5%–10% of your total daily calories, or about 20–50 grams a day. The typical fat intake on a keto diet is around 70%–80% of your total daily calories, with 10%–20% of your daily calories coming from protein.

Macronutrients on Keto

A typical keto diet contains:

• 5%–10% carbohydrate intake (about 20–50 grams a day)
• 70%–80% fat intake
• 10%–20% protein intake

Because the keto diet is very high in fat, it begs the question of whether it can affect your cholesterol levels—for better or for worse. This is a valid concern, as cholesterol levels are linked to heart disease risk. However, the effect of a keto diet on heart health isn't so clear-cut.

This article will discuss the types of cholesterol in the body and the results of research into how a ketogenic diet may influence those levels.

Cholesterol Explained

Cholesterol is a waxy, fatlike substance found in the cells of your body. It helps your body build cell membranes, vitamin D, and hormones. However, too much cholesterol can lead to heart health problems.

There are different types of cholesterol, and each has a different effect on heart health, such as:

• Low-density lipoprotein (LDL) cholesterol is known as the "bad" cholesterol because it contributes to heart disease by adding to fatty buildup in the arteries. This fatty buildup leads to a narrowing of the arteries and a disease called atherosclerosis. Atherosclerosis increases the risk for heart attack and stroke.
• High-density lipoprotein (HDL) cholesterol is known as the "good" cholesterol because it can help protect against heart attacks and strokes. HDL cholesterol helps remove some LDL cholesterol from the arteries, which may protect against heart disease.
• Triglycerides are not a form of cholesterol, but they are the most common type of fat, or lipid, in your body. Your body converts extra calories from the food you eat into triglycerides, which are then used for energy between meals. A high triglyceride level combined with a high cholesterol level increases your risk for heart disease.

Your total cholesterol level is a measure of both LDL and HDL cholesterol, plus 20% of your triglycerides.

How a Keto Diet May Influence Cholesterol 

There has been some research done on low-carbohydrate diets and their effects on cardiovascular health. It can be hard to draw specific conclusions on the topic, though, because many of the studies are short term (less than two years long), are of a small sample size, and examine different variations of very-low-carb diets.

Nevertheless, we are starting to understand a little bit more about how very-low-carbohydrate, or ketogenic, diets may affect cholesterol levels. Below is a summary of some of the research studies.

Position Statement

In 2019, the National Lipid Association released a position statement on diets low or very low in carbohydrates (including ketogenic diets) and their relation to body weight and other cardiometabolic risk factors.

Based on the evidence reviewed, the association concluded that these diets do yield weight loss but are not superior to other weight-loss diets. 

However, they do seem to offer greater benefits for appetite control, reducing triglycerides, and decreasing the need for medication in people with type 2 diabetes. Studies showed mixed results on LDL cholesterol levels, with some demonstrating an increase.

Low-Calorie vs. Ketogenic Diet

A 24-week study done in Kuwait compared a low-calorie versus very-low-carbohydrate ketogenic diet in adults with and without diabetes. Dietary counseling was provided at the beginning of the study and on a biweekly basis.

At its conclusion, the study showed both diets resulted in significant weight loss. Also, the very-low-carbohydrate ketogenic diet significantly decreased triglycerides, total cholesterol, and LDL cholesterol levels, with a noticeable increase in HDL cholesterol levels in the people studied.

Ketogenic Diet in Diabetes

One small study had 11 women with type 2 diabetes follow a ketogenic diet for 90 days. After the 90 days, results revealed an increase in HDL cholesterol, a decrease in triglycerides, and no significant changes in LDL cholesterol among participants. Additionally, the study showed decreased body weight and blood pressure.

Ketogenic Diet in a CrossFit Group

Studying healthy people, a 12-week investigation looked at the effects of a ketogenic diet in people who regularly trained in CrossFit. Twelve people participated in the study involving the high-intensity, interval-training workout. Five of the study participants were in the control group and continued eating a regular diet, while seven people followed a ketogenic diet.

The study concluded that changes in HDL cholesterol and triglycerides were not significant and were similar among participants in both groups. In contrast, LDL cholesterol increased nearly 35% in those following the keto diet along with CrossFit.

Ketogenic vs. Low-Fat and Low-Carb Diets

A 2013 review of studies comparing a very-low-carbohydrate ketogenic diet to a traditional low-fat diet showed that participants following the low-carb keto diet experienced decreases in body weight and diastolic blood pressure, along with increases in HDL cholesterol and LDL cholesterol.

Another review of studies in 2016 comparing low-fat and low-carbohydrate diets yielded similar results. The authors found that participants on low-carbohydrate diets had a greater weight loss and higher increase in HDL cholesterol but also showed higher LDL cholesterol levels than those following a low-fat diet.

Effect of Saturated Fat

A review of low-fat diets versus low-carb, high-fat diets greater than 12 months long looked at the effects on cholesterol levels in overweight or obese people.

Researchers found that decreases in total cholesterol and LDL cholesterol levels were significantly more noticeable in those following low-fat diets. In contrast, an increase in HDL cholesterol and a reduction in triglyceride levels were more apparent in high-fat-diet participants. 

Whether cholesterol increases or decreases largely depends on how the very-low-carbohydrate ketogenic diet is followed—particularly with the types of fats consumed.

The study authors further found that in high-fat diets, decreased total cholesterol levels were associated with lower intake of saturated fat and higher polyunsaturated fat intake. In comparison, increased HDL cholesterol was related to a higher intake of monounsaturated fat.

Lower saturated fat intake was marginally related to lower LDL cholesterol levels. Additionally, increased triglyceride levels were associated with higher intakes of carbohydrates.

Ketogenic Mediterranean Diet with Phytoextracts

An Italian study in 2019 looked at 106 overweight or obese people who ate a diet known as the ketogenic Mediterranean diet with phytoextracts (KEMEPHY) and took a daily multivitamin supplement over six weeks. Subjects were allowed to consume unlimited calories in a diet made up of green vegetables, olive oil, fish, meat, and other high-quality proteins, along with specific food supplements and herbal extracts.

The results showed a significant decrease in body mass index (BMI), total cholesterol, LDL cholesterol, triglycerides, and blood glucose levels. There was also a significant increase in HDL cholesterol levels.

Research Conclusions

Based on these studies, it might be surmised that a keto diet can improve total cholesterol and HDL cholesterol. However, this diet may have no significant effect—or it may even increase—LDL cholesterol levels. Overall, larger, longer-term studies are needed in order to draw a precise conclusion on the effects of a ketogenic diet on cholesterol and, in turn, heart health.

How Genetics Plays a Part

While the ketogenic diet may be safe for most people, it might not be healthy for others to follow. A ketogenic diet could increase LDL cholesterol levels in some people at high risk for heart attack and stroke.

In particular, people with an inherited condition called familial hypercholesterolemia should always consult with their healthcare provider before trying a ketogenic diet. Familial hypercholesterolemia is marked by very high LDL cholesterol levels and an increased risk of premature heart disease. The American Heart Association has state that only 10% of people with familial hypercholesterolemia are aware they have it.

Additionally, some people have a rare genetic condition that affects how LDL particles are regulated, causing high LDL cholesterol levels. The genetics causing this response isn't completely understood, but the APOE gene, which provides instructions for making a protein called apolipoprotein e, may be one of several factors involved. People who have this inherited genetic condition should avoid the keto diet.

Frequently Asked Questions:

What specific foods should I eat on keto to also maintain good cholesterol?

Consuming mostly unsaturated fats, compared to saturated fats, while on a keto diet may improve cholesterol levels, especially LDL cholesterol levels. Unsaturated fats are found in foods such as:

• Plant oils like olive, avocado, sunflower, corn, and canola oils
• Avocados
• Olives
• Fatty fish, including salmon, sardines, tuna, and mackerel
• Nuts and nut butters, including peanuts, almonds, cashews, pecans, and walnuts 
• Seeds, such as flax, sesame, sunflower, and chia

The keto diet is also typically lower in fiber, so maximizing the small number of carbohydrates allowed while following keto can benefit not only cholesterol levels but also gut health. Choosing non-starchy fruits and vegetables like avocados, tomatoes, asparagus, broccoli, and spinach can help.

Additionally, many people cannot follow the keto diet in the long term, so having a clear and defined plan for how to transition off the keto diet is important to help retain any positive health benefits acquired.

Is keto healthy?

A ketogenic diet may affect your health positively or negatively, depending on your individual health history and how you follow the diet. The keto diet can be a safe and healthy diet when consuming mostly healthy, unsaturated fats instead of mainly saturated fats.

It's also best to be under the care of a doctor before and during a keto diet to ensure it's safe and healthy for you.

Is keto a good choice if you have both high cholesterol and high blood pressure?

If you have high cholesterol and high blood pressure, it's important to talk with your doctor before deciding to go on a ketogenic diet. Your doctor will take your specific circumstances into consideration, such as overall health, the medications you take, and other risk factors, before approving a keto diet.

With some studies showing keto may potentially improve cholesterol and blood pressure levels, it might be worth asking your healthcare professional about it.

How does keto affect your arteries?

How the keto diet affects your arteries depends on your individual health and the types of fats consumed while on the diet. Saturated fats have been shown to negatively affect your cholesterol levels mainly by increasing your LDL cholesterol levels. This can contribute to plaque buildup in your arteries.

However, unsaturated fats have the opposite effect on heart health by decreasing LDL cholesterol and increasing HDL cholesterol levels. This can improve your heart health, decreasing your risk of heart attack and stroke.

How much sodium and cholesterol do you consume on keto?

There are no specific guidelines for how much sodium and cholesterol should be consumed while following a ketogenic diet.

The Dietary Guidelines for Americans recommends that healthy adults consume less than 2,300 milligrams of sodium—equal to about 1 teaspoon of table salt—per day. The dietary guidelines do not list specific limits on dietary cholesterol, as recent research has shown that dietary cholesterol doesn't have as much of an effect on blood cholesterol as once thought.

However, it is important to note that many foods high in cholesterol are also high in saturated fat and, in effect, may increase the risk of heart disease due to the saturated fat content. Two exceptions to this are eggs and shrimp. Because of this correlation, it might be wise to limit the amount of foods you take in that are high in both dietary cholesterol and saturated fat while following keto.

Summary

The ketogenic diet is very low in carbohydrates and high in fat. How this affects HDL and LDL cholesterol, triglycerides, and heart health is under investigation. Studies on the connection generally have been short term and have reached a variety of conclusions.

One factor that affects choleserol outcomes with keto is the type of fats consumed, with unsaturated fats being preferred. Genetics may also play a role in how the ketogenic diet influences cholesterol levels in an individual.

A Word From Verywell

Close communication with your healthcare professional and regular testing are key factors in starting any new diet regimen, including the keto diet, to ensure a safe path forward. If you choose to follow a keto diet, be sure to check with your doctor on its safety for you. Also, get your cholesterol levels tested before and during the diet to be confident they aren't changing to unsafe levels. 

If you plan to follow the ketogenic diet only for a short while, make a plan with your doctor on how you should transition off of it to help ensure success in the long term.

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