Every proponent of the ketogenic diet is countered by someone who warns about the negative consequences on your heart. The concern is that eating a diet that is extremely rich in fat, moderate in protein, and very low in carbohydrates can cause your cholesterol levels to soar, increasing your chance of developing heart disease.
Certainly, the concern is justified. On the keto diet, you consume up to 80% of your daily calories from fat and limit yourself to 20–50 grams of net carbohydrates, a term used in well-known diets like the keto and Atkins but not one that is recognized by the medical profession. (According to Atkins, to get net carbohydrates, deduct fiber and sugar alcohols from the total amount of carbs.) All of this indicates that you will consume a large amount of fat each day. In an effort to achieve your quota, you may choose unhealthy foods like butter, coconut oil, and animal fat. According to the American Heart Association, all of these include saturated fat, which has been related to having a bad cardiovascular system (AHA). (The goal of the keto diet is to transition your body into the ketosis state, which is when it starts burning fat instead of carbs.)
However, it’s not as easy to understand as it may sound how the keto diet affects heart health. The ketogenic diet may not have the negative effects on your cholesterol that were previously believed.
“When you look at the data, a few things become obvious. According to demographic studies and clinical trials, the keto diet’s effect on lipids is negligible, asserts Daniel Soffer, MD, a physician who specializes in internal medicine and lipidology at Penn Medicine in Philadelphia. The National Lipid Association, a group devoted to treating lipid issues, has Dr. Soffer as a member. A policy statement on low-carb and very-low-carb ketogenic diets and their connection to lipids was published in the Journal of Clinical Lipidology by the National Lipid Association in October 2019. (PDF). The majority of the time, according to study, keto results in modest triglyceride reductions, small changes in heart-protective HDL (or “good”) levels, and negligible changes in LDL (or “bad”) levels. The review points out that some research demonstrate an increase in LDL on low- or extremely low-carb diets. (Long-term research are scarce, though.)
Whether these values change for the better or worse, especially for HDL, is primarily dependent on how well you follow the keto diet. The lack of a single ketogenic diet is one issue. There are various approaches to adopting it, and while some people are cautious about the sorts of fats they consume, others are not, according to Soffer.
To support his claim, a previous article mentioned that in human research on both normal-weight and obese individuals, keto diets are typically linked to lower levels of total cholesterol, higher levels of HDL, lower levels of triglycerides, and lower levels of LDL. The review notes that different findings from other studies show a rise in LDL or no change at all. The authors note that in studies where LDL levels dropped, participants consumed a low-carb diet that was high in beneficial unsaturated fat and low in harmful saturated fat.
More than 360 overweight and obese patients participated in a previous study that was mentioned in the article above that compared a low-calorie diet with a very low-carb, high-fat diet (what would be considered a keto diet). There were individuals with and without diabetes. The keto group’s total cholesterol, triglycerides, and LDL levels dropped after around a year, while HDL levels increased.
Understanding Potential Effects of Keto on Your Cholesterol Levels
Think about your starting triglyceride level to get a sense if the keto diet might raise your cholesterol. Triglycerides are a different type of blood lipid your body utilizes for energy, and high levels of both can result in fatty deposits that clog arteries, as noted by the AHA. Less than 150 milligrams per deciliter (mg/dL) are considered normal levels. “The cutoff for increased triglycerides is 150 mg/dL, and around a fifth of the population has levels over this level. This is a significant portion of the population, thus it happens frequently,” claims Soffer.
Keto is probably safe to attempt if your levels are normal. “The impact of keto is low or nonexistent for persons with normal or excellent triglyceride levels,” claims Soffer. However, Soffer contends that while it may seem counterintuitive if you have type 2 diabetes, insulin resistance, abdominal obesity, or any of these conditions, and your triglycerides are high, you should avoid going on a ketogenic diet because of its low carb content’s potential to reduce insulin resistance and raise triglycerides.
Additionally, research points to this result. 34 obese older individuals were the subject of a small randomized, controlled study that was published in August 2020 in Nutrition & Metabolism. In comparison to the low-fat group, those who followed a very low-carb diet shed three times as much visceral fat; they also experienced greater improvements in insulin sensitivity, triglyceride levels, and HDL cholesterol.
And to add another layer, there is a connection between triglycerides and HDL cholesterol. According to the AHA, HDL is often low when triglycerides are high. In the opposite direction, Soffer asserts that “everything that reduces triglycerides will likewise [tend] to enhance HDL.” Keeping in mind that HDL is a form of “good” cholesterol that, according to the AHA, transports some LDL from the bloodstream into the liver where it can be processed and excreted, raising HDL is ultimately beneficial for your heart.
However, the aforementioned Nutrition & Metabolism study only included 34 participants, indicating that further research (particularly larger, longer-term studies) is required before experts can fully comprehend the true effects of keto on insulin resistance and triglycerides.
Following a ketogenic diet decreased fasting blood glucose and — in eight studies — also decreased HbA1c levels, according to a bigger study pool of 567 diabetics drawn from across 13 studies and published in Nutrition & Diabetes in November 2020. (a measure of average blood sugar over time). The authors note that evidence indicates a 1% decrease in HbA1c could reduce the risk of a heart attack by 14%; on average, HbA1c decreased by roughly 1.5%.
However, the evidence is conflicting when it comes to following the keto diet to lose fat or weight. One significant warning: There isn’t enough evidence to demonstrate whether keto can lead to long-term results. According to a prior assessment, weight loss on the keto diet reaches its maximum after five months, after which there is a gradual weight increase. Additionally, a meta-analysis of 38 research that evaluated low-carb and low-fat diets in the December 2020 issue of Nutrients found that each had distinct short-term impacts on the body. In comparison to low-fat diets, low-carb diets were linked to greater weight loss (approximately 3 pounds) and better HDL and triglyceride values. On the other hand, low-fat diets reduced LDL and total cholesterol more successfully. The few studies that looked at outcomes beyond two years found the results were no longer significant, presumably because people had problems staying with it over the long run. Nevertheless, these results were only useful for the short-term.
How Keto Could Impact LDL Cholesterol
It’s not entirely apparent how eating a high-fat, very low-carb diet affects your LDL. LDL is the form of cholesterol that has been connected to atherosclerosis, which can raise your risk for heart disease and stroke, as stated by the AHA once more. It could increase, decrease, or essentially remain the same. Theoretically, Soffer adds, your LDL may be stable if you follow a ketogenic diet to reduce weight and have a normal triglyceride level. Similar to how your LDL may remain the same if you started off with high triglycerides and that number drops while on keto.
The basic lesson is that the cholesterol jump that some people observe after beginning the diet may not be caused by keto alone. However, if you increase your consumption of saturated fat as a result of becoming keto, your LDL levels are likely to go up. According to Soffer, it has been “proven repeatedly” that increasing saturated fat intake raises LDL.
People with a genetic mutation that affects the regulation of LDL may be harmed by keto.
If you are one of the people who has an inherited genetic mutation that changes how LDL particles are regulated, then things could become potentially deadly. According to Soffer, “These people’s LDL levels can rise if they adopt a keto diet.” The impact of the diet on your personal health is what counts most, yet this conclusion doesn’t occur frequently enough to distort general findings in population research. The genetics underlying this response aren’t fully understood, he adds, adding that it’s a long-recognized phenomena that hasn’t been well-publicized. (The APOE gene could be one, he thinks, but it’s probably not the only one.)
You might not be aware that you have familial hypercholesterolemia, another name for a preexisting genetic abnormality (FH). In actuality, only 10% of those who have FH are aware of it, according to the AHA. Knowing your family’s medical history, particularly any young people who have experienced a heart attack, is crucial and can steer your provider in the appropriate way. A low-carb diet may occasionally be advantageous for those with FH who also have insulin resistance, according to data, suggested a previous review. You shouldn’t try to figure this out on your own. Instead, it serves as even additional justification for consulting your physician about dietary changes, especially if you already have other medical issues like high cholesterol.
However, “for someone with this genetic tendency, [the keto diet] can be a hazardous diet,” adds Soffer. The average person is unlikely to detect anything abnormal about their cholesterol. It takes at least ten years of high LDL levels before damage is done, according to him, so a brief six-month increase in cholesterol is not worrisome. However, if this is your diet for the rest of your life, it could be harmful.
Should You Stay Away From Keto If You Have High Cholesterol?
High cholesterol does not automatically rule you out of the ketogenic diet. According to clinical dietitian Susan Ryskamp, RDN, of Michigan Medicine’s Frankel Cardiovascular Center in Ann Arbor, “we’re seeing pretty fantastic cardiovascular effects with a keto diet.”
In order to improve indicators like triglycerides, A1C, blood pressure, and body mass index, physicians will want to consider the big picture (BMI). “On keto, we feel patients are at less of a cardiovascular risk if they lose weight, have their BMI closer to, if not under 30 (under the criterion for obesity), and these biomarkers improve,” adds Ryskamp.
Ryskamp would probably recommend another diet first if a patient has substantially increased triglyceride levels that were over 1,000 mg/dL (keep in mind that under 150 is normal). A triglyceride level of 300, however, can still be acceptable with careful observation and regular lipid testing. Most of the people I see can go on keto, according to her.
According to Ryskamp, people develop heart disease for various reasons (genetics, artery hardening), and each cardiovascular patient has a distinct response to treatment. She claims that while not everyone may choose to go keto, certain doctors may advise it. Keto is not the only choice, as a study published in November 2019 in Clinical and Scientific Debates on Atherosclerosis demonstrates. The authors state that there are “other diets that are as effective, more enduring, and safer.” A plant-based diet rich in fruits, vegetables, legumes, whole grains, and lean animal or vegetable protein is still advised by the AHA as a heart-healthy diet.
How to Adopt a Heart-Healthy Keto Diet
The possibility of eating any type of fat is one of the appeals of the ketogenic diet. You should not enter such frame of mind. According to Ryskamp, “I advise patients to select cardioprotective [unsaturated] fats, such as nuts, nut butter, seeds, avocado, and extra virgin oils, like olive oil.” In a similar vein, stay away from using foods high in saturated fat (such as butter) as your main sources of fat.
Not only fats, but also making the most of the meager amount of carbohydrates you are permitted, are crucial. It can be difficult to get enough fiber, so you should focus on eating a lot of low-GI vegetables (nonstarchy choices such as spinach and broccoli). In the end, she claims, the advantages come from substituting items that are heart-healthy, like unsaturated fats, for those that doctors believe are harmful to general heath, such processed carbs.
It’s been said time and time again: If you’re significantly altering your diet, including going keto, you should speak to your doctor first to ensure that it’s healthy for you and your particular health concerns. Additionally, you should have your lipid levels evaluated before and during the keto diet so that your doctor can check for an increase in cholesterol and decide whether this is a healthy diet for you.
One of the main worries, according to Soffer, is that if you leave the ketogenic diet, you continue eating a high-saturated-fat diet combined with the traditional American diet, which is high in calories and heavy in refined grains and meats but low in fruits and vegetables (PDF). Since the keto diet is so restrictive, most individuals don’t stick with it for very long. As a result, you should keep an eye on your diet and make proper preparations for quitting the diet.
Conclusion: Try the Keto Diet to Lower Your Cholesterol
Before starting a ketogenic diet, check with your medical team if you have excessive cholesterol or triglycerides. Continue to ask for their assistance if you receive the all-clear. There are many popular publications available on how to follow a ketogenic diet, but Ryskamp believes patients need more help, direction, and ongoing dialogues about whether it is effective for them. It’s a tool that someone can use to better their health, but she cautions that it might not be the best tool for them or the best tool for how they’re using it.