Ketogenic Diet and Cholesterol Changes—Risks and Rewards

Keto is an increasingly popular diet these days. And it’s no surprise—who wouldn’t get excited about eating bacon and losing weight? Beyond weight loss, some recent studies have demonstrated that ketogenic diets offer additional benefits for people with diabetes. The ketogenic diet is high-fat, low carb, and sufficient protein to allow the body to burn fat and use ketones instead of glucose for fuel. This can lead to weight loss, as well as reductions in A1C and other cardiovascular risk factors. Originally, the ketogenic diet was developed as a method for treating medication-resistant epileptic seizures in children. It was not used as a weight loss tool because of concern among the medical community that such a high-fat diet could increase cholesterol, triglycerides, and overall risk of heart disease.

Cholesterol and triglycerides are both types of lipids, or fat molecules. Triglycerides are form of fat that circulates in the bloodstream and can be stored in fat cells or used for energy to meet a body’s needs. High levels of triglycerides can lead to plaque build up on arteries and can cause inflammation of the pancreas. Cholesterol is a wax-like molecule that is used to create important hormones such as androgens and other compounds like vitamin D and bile salts. When excess cholesterol is present in the blood stream, it builds up in arteries and veins, causing plaques and restricting blood flow. These plaques can lead to heart disease, heart attack, or stroke.

Cholesterol is characterized by the lipoprotein carrier that transports it. High-density lipoprotein (HDL) scavenges cholesterol and returns it to the liver, earning its moniker “good cholesterol”. Low-density lipoprotein (LDL) is commonly called “bad cholesterol”. This carrier is larger and lighter. Because of this, it sticks to surfaces like artery walls. LDL is responsible for dangerous blood vessel blockages. There are two different measures of LDL. LDL-P is the number of LDL particles in the blood. LDL-C represents the amount of LDL with cholesterol bound to it. When looking at cardiovascular risk, LDL-P may be the best measure. Most standard tests report an LDL-C value based on the Friedewald equation in which LDL is calculated by subtracting both HDL and triglycerides/5 from total cholesterol. Because of this calculation, the reported LDL-C is influenced by changes in other lipid levels. Together, LDL, HDL, and triglycerides all contribute to cardiovascular health. Ideal blood lipid ranges for adults are <200 mg/dL (total cholesterol), <100mg/dL for (LDL cholesterol), and >60mg/dL (HDL cholesterol), and <150mg/dL (triglycerides). Experts also recommend having low total cholesterol/HDL and triglyceride/HDL ratios for reduced heart risk. In fact, in the long-term Medical, Angioplasty, or Surgery Study (MASS-II), a high triglyceride/HDL ratio was the only lipid measurement that correlated with elevated risk of a major cardiac event.

Some of our cholesterol level is controlled by our genes, but diet can influence the amount of LDL and HDL cholesterol in our bodies. According to the Harvard School of Public Health, “the biggest influence on blood cholesterol level is the mix of fats and carbohydrates in your diet—not the amount of cholesterol you eat from food.” Some individuals, however, respond strongly to cholesterol in their diet.

Increased lipid and cholesterol levels have been reported in people on ketogenic diets. According to lipidologist Dr. Sarah Hallberg, “cholesterol levels improve for most people when in ketosis… but there can be a temporary rise in LDL-P or LDL-C if [a person] is losing a significant amount of weight.” In some individuals, ketogenic diets raise LDL and total cholesterol levels for more than a brief time. In the IUH/Virta diabetes reversal study, a significant number of patients experienced an increase in LDL-C over the course of a year. Elite athletes on ketogenic diets demonstrated increased LDL and total cholesterol levels as well. These people may be part of the population of “responders” whose cholesterol levels are closely linked to their diet.

According to the latest guidelines of the American College of Cardiology (ACC), LDL is just one piece of a complex puzzle when it comes to determining an individual’s cardiovascular risk. They recommend assessing a variety of factors including age, sex, race, bodyweight, blood pressure, medication use, family history of heart disease, inflammation, history of diabetes, and triglyceride levels, in addition to looking at blood cholesterol levels. The ketogenic diet seems to have positive effects on other blood lipids involved in cardiovascular health, including HDL, triglycerides, and the triglyceride/HDL ratio. In fact, patients on a Virta Health-formulated keto diet lowered their cardiovascular risk by nearly 12% according to the ACC 10-year risk calculator, by reducing several key factors including triglycerides, blood pressure, weight, and A1C, and increasing HDL. Patients with type 2 diabetes also reduced their need for insulin and 60% reversed their diabetes. Another recent study of a ketogenic diet in obese subjects revealed decreases in BMI, triglycerides, total cholesterol, and LDL over the course of 6 months. Patients also exhibited increases in HDL. It is important to note that for this study, patients consumed 80-100g of lean protein and all additional fat was in the form of poly- and mono-unsaturated fat. This diet differed from other ketogenic diets that allow for much higher consumption of saturated fat. It is possible that the observed differences in cholesterol may relate to this key difference.

Since a ketogenic diet offers significant health benefits, especially for individuals with diabetes, many people think the benefits outweigh the potential risk associated with increases in LDL. Still, most experts agree that elevated LDL is a major cardiovascular risk factor, and is not something you should ignore. What can be done if this miracle diet raises your LDL cholesterol?

First, talk to your doctor. You may want to check what test was performed. If possible, try to obtain an LDL-P instead of LDL-C. In addition, calculate your triglyceride/HDL ratio as another, perhaps more meaningful, measure of cardiac health.  

The LDL increase may be a temporary consequence of significant weight loss. If levels don’t go back to normal, you can ask your doctor about  switching fat sources from saturated to poly- and monounsaturated fats like olive or avocado oil. You can also ask about increasing consumption of fiber-rich, low-carb vegetables. Fiber can reduce cholesterol naturally. If your LDL-P is significantly elevated and/or these modifications do not help lower your cholesterol, your doctor may recommend adding a statin. In general, patients who are already on a statin do not need to change their dose when starting a ketogenic diet.

Elizabeth Hubscher

Elizabeth Hubscher is a writer and scientist based in Raleigh, North Carolina. She earned her doctorate in Molecular Toxicology in 2007. Libby works as a community college life sciences instructor and medical writer. Her writing has appeared in scientific journals, textbooks, and literary journals. In her free time, Libby enjoys hanging out with her husband, two children, and their Labrador, Auggie. She is passionate about promoting health and advocacy for people struggling with autoimmune diseases and chronic illnesses.

Elizabeth Hubscher

Elizabeth Hubscher is a writer and scientist based in Raleigh, North Carolina. She earned her doctorate in Molecular Toxicology in 2007. Libby works as a community college life sciences instructor and medical writer. Her writing has appeared in scientific journals, textbooks, and literary journals. In her free time, Libby enjoys hanging out with her husband, two children, and their Labrador, Auggie. She is passionate about promoting health and advocacy for people struggling with autoimmune diseases and chronic illnesses.