The ketogenic (keto) diet has gained immense popularity in recent years. People may choose to eat keto for health and weight-loss reasons. However, the keto diet is also sometimes recommended for certain medical conditions, such as obesity, type 2 diabetes, metabolic syndrome, and epilepsy.
Some people with high cholesterol levels try the keto diet in the hope that it will reduce their cholesterol levels. However, some members of the scientific community are concerned that this could do more harm than good.
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The keto diet is a high-fat and low-carbohydrate diet.
The macronutrient distribution of the keto diet is as follows:
Fat: between 55% and 60%
Protein: between 30% and 35%
Carbohydrates: between 5% and 10%
A 2000-calorie-a-day diet comes to around 20–50 grams of carbohydrates, which is approximately two or three slices of bread.
Common foods eaten on the keto diet are coconut oil, butter, eggs, avocado, cheese, fish, meat, nuts, seeds, seafood, and vegetable oils.
Saturated and unsaturated fat can be eaten without restrictions on a typical keto diet. However, it’s important to remember the general diet recommendations of limiting saturated fat intake. The Dietary Guidelines for Americans¹ recommend limiting saturated fats to less than 10% of one’s daily caloric intake.
The keto diet heavily restricts starchy foods such as legumes, grains, starchy vegetables (such as potatoes), and most fruits. Some of these foods are often encouraged by nutrition experts because they are packed with essential nutrients and antioxidants.
A ketogenic diet can be potentially dangerous for some people. So before starting this diet, it’s important to consider the following factors.
Genetics can influence the impact that a diet has on cholesterol levels.
Some people are predisposed to high cholesterol due to a genetic mutation inherited from one or both of their parents — this is called familial hypercholesterolemia (FH).
People with FH should not follow a keto diet because some people can experience extreme effects of a keto diet on LDL cholesterol levels due to their genetic factors. The National Lipid Association has shown concern regarding this. People with FH who want to try the keto diet should do so under close medical observation.
Some patients with severe hypertriglyceridemia may have dysfunction of an enzyme called lipoprotein lipase that occurs due to genetic or acquired causes. They may also have a predisposition to hypercholesterolemia and acute pancreatitis. These patients are also advised to follow a low-fat diet — hence the keto diet can be dangerous and is not recommended.
Please keep this information in mind before considering a ketogenic diet. If you have any concerns about how a ketogenic diet could impact your health, it’s always best to speak to a doctor first.
The keto diet aims to cause the body to enter a metabolic state called ketosis. Ketosis is when the body burns ketone bodies instead of glucose because all the body’s carbohydrate stores have been used up. Ketone bodies are metabolic compounds formed from the breakdown of fat in the liver.
When ketone bodies accumulate in the blood, it suggests the person is in a state of ketosis. Ketone bodies can be used for energy by the heart, brain, kidneys, and muscle tissue.
During the process of ketogenesis and due to low blood glucose levels, insulin secretion, which is stimulated by blood glucose levels, is also low — this significantly reduces the stimulus for fat and glucose storage. This will translate to fewer insulin spikes/accumulation (improving insulin sensitivity and type 2 diabetes) while also storing less body fat, aiding in weight loss.
Cholesterol is a waxy, fatty substance that travels through the bloodstream. It’s found in animal-based food products and is produced naturally in our bodies.
Cholesterol is important for building cell membranes and producing vitamin D and hormones. Cholesterol is carried through the body by different types of lipoproteins. The main two are high-density lipoprotein (HDL) cholesterol and low-density lipoprotein (LDL) cholesterol.
LDL cholesterol is known as “bad” cholesterol because it can deposit in arteries, blocking them and leading to a higher risk of developing atherosclerosis, which can lead to various cardiovascular issues, heart attack, and stroke.
HDL cholesterol is known as “good” cholesterol. It helps to remove LDL cholesterol from the blood. This can help to protect against the cardiovascular-related complications of having high LDL cholesterol.
When someone has high cholesterol, that person either has an abnormally high total cholesterol level due to high LDL cholesterol levels or low HDL cholesterol in the bloodstream, or their total cholesterol level could be within the normal values, but their LDL levels are high, worsening the LDL/HDL optimal ratio.
Diet plays a large role in cholesterol levels. Research² has shown that although cholesterol in foods has a minimal impact on serum cholesterol and cardiovascular risks, saturated and trans fats have a large impact on them.
The current dietary advice for people with high cholesterol is to:
Limit foods high in cholesterol
Limit saturated fat to <7% of daily calories
Eat foods high in soluble fiber
Eat an abundance of fruits and vegetables
Eat foods high in omega-3 fatty acids
Make a large part of your daily fat intake from mono and polyunsaturated fatty acids
Reduce alcohol intake for people who drink excessively
Although the keto diet is gaining popularity, it’s not regularly recommended by experts or healthcare professionals for people with high cholesterol.
Eating keto may cause high cholesterol in some people.
Whether or not keto causes high cholesterol likely depends on the kinds of fat eaten and the quality of carbohydrates consumed.
Eating foods with a lot of saturated fat, cholesterol, and trans fat is associated with high LDL cholesterol levels. A higher intake of unsaturated fat is associated with lower LDL cholesterol levels.
The research on whether a keto diet causes high cholesterol is mixed.
Some research suggests that the keto diet can increase LDL cholesterol levels. Most studies find this increase in cholesterol is due to study participants eating foods high in saturated fat.
There was a case study³ of a woman who followed the keto diet for 30–40 days and experienced a rapid increase in LDL and total cholesterol. However, it wasn’t determined whether this increase in cholesterol was directly due to the keto diet or whether it was due to the cholesterol in the fat tissues becoming mobilized due to the woman’s rapid weight loss.
Numerous studies compared the difference in blood lipids (fats) in low-carbohydrate and balanced diets, or high-carbohydrate, low-fat diets. These studies found that people following low-carbohydrate diets were more likely to have higher total cholesterol and LDL cholesterol.
A study⁴ of 17 healthy young and normal-weight women who followed a keto diet rich in saturated fats for four weeks resulted in a harmful blood fat profile with increased LDL cholesterol in all women.
Despite some evidence suggesting the keto diet increases cholesterol, it may also help to reduce cholesterol levels. Again, this depends on how well-planned the diet is and the types of fats eaten — if the majority of the fat content is from poly and monounsaturated fats, the results could be positive in improving the person’s lipid profile.
People with high cholesterol who are considering trying the keto diet should speak with a medical professional before making any significant dietary changes. People who follow the keto diet should have their body weight, total cholesterol, and LDL cholesterol levels checked and their glucose levels monitored.
A high sugar and refined carbohydrate diet are also associated⁵ with high cholesterol levels. On the keto diet, sugary foods (carbohydrates) are heavily restricted, so the keto diet may help lower cholesterol in this way.
Some research suggests that the keto diet leads to an improvement in the lipid profile, and this has been backed up by several studies.
One study⁶ was done on 66 obese but generally healthy men with either high or normal cholesterol levels who followed the keto diet. The results showed that both groups of men with high and normal cholesterol levels experienced a reduction in weight and LDL cholesterol as well as a rise in healthy HDL cholesterol after being on the diet for 56 weeks.
A study⁷ on 83 obese men and women with high cholesterol looked at the impact of being on the diet for 84 weeks. The participants experienced a reduction in total cholesterol and an increase in HDL cholesterol. It also reported a significant reduction in LDL after 24 weeks of the keto diet.
These participants were asked to ensure that 20% of their dietary fat was saturated and 80% was unsaturated. This study found the keto diet to be safe for long-term use.
Further studies⁸ also suggest that the keto diet can raise HDL cholesterol levels. This is beneficial because HDL cholesterol helps move LDL cholesterol from the bloodstream to the liver, which will be metabolized and removed from the body. Consuming lots of omega-3 polyunsaturated fatty acids during the keto diet may help increase HDL cholesterol levels.
Other factors associated with reducing cholesterol and maintaining healthy levels, including managing diabetes, reducing alcohol intake, stopping smoking, regularly exercising, and losing weight if needed, are still important, even for people following and benefitting from a keto diet.
Several factors influence how the keto diet affects cholesterol levels.
Obesity and being overweight are associated with high cholesterol levels. A study⁹ in overweight and obese people found that both a low-calorie diet and a ketogenic diet led to a reduction in cholesterol, but that reduction was more significant in people following the keto diet.
Losing weight and maintaining it at a healthy level is a recommended lifestyle change that will help manage and reduce cholesterol. A 5- to 8-kg loss in weight can reduce LDL cholesterol by 5mg/dL and increase HDL cholesterol by 2 to 3mg/dL.
A low-calorie diet can help someone lose weight. In turn, this could help reduce their cholesterol levels. However, this can be influenced by the macronutrient content of the low-calorie diet the person is following and the type of fats they eat.
Some studies suggest that very low-carbohydrate diets, such as the keto diet, can reduce one’s appetite by influencing hunger hormones. This is thought to lead to a lower calorie intake, which means that the keto diet may contribute to weight loss and indirectly reduce cholesterol.
Compared to less restrictive low-calorie diets, keto diets may be challenging to maintain long-term.
The keto diet can have variable effects on LDL cholesterol and total cholesterol. But if you are opting for a keto diet, try limiting saturated fats and eating an abundance of unsaturated fats. Otherwise, LDL levels may remain as they are or could even increase.
Healthy foods you should opt for include:
Lean meats and seafood - including chicken breast, turkey, tuna, and salmon
Plant proteins - including tofu, legumes, and beans
Fat-free milk and dairy products
Soy milk and other plant-based milk products
High-fiber foods and greens
Healthy fats - including unsaturated fats from avocados, olive oil, and nuts
The evidence on whether the keto diet increases or decreases LDL cholesterol is mixed. The effect is likely influenced by the amount of saturated, trans, and unsaturated fat in one’s diet.
While focusing on eating unsaturated fats and limiting saturated fats may decrease cholesterol, a high intake of saturated fats can increase it.
People with high cholesterol levels who are considering the keto diet should speak with a doctor or a dietician to ensure it will be a safe and effective approach to improving overall health.
Ketogenic diet (2022)
Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force (2019)
Prevent high cholesterol | Centers for Disease Control and Prevention (CDC)
Keto diet and cholesterol: Friend or foe? | VeryWellHealth
Ketogenic diet and lipids | Heart UK