Can the Keto Diet Help Prevent or Manage Heart Disease?
The trendy diet is high in fat — but that doesn’t necessarily mean it’s bad for your heart. Cardiologists weigh in on what you need to know about keto and heart disease.
Some keto followers brag about how much butter and bacon they can eat. So if you have heart disease, are at risk for it, or are generally concerned about your heart health, you may be confused about whether the keto diet — made up of at least 70 percent fat and very few carbs depending on the version of keto you follow — is bad for your heart. The short answer is that you may be able to try the keto diet but only under close supervision with a keto-knowledgeable doctor or registered dietitian. For optimal heart health, many cardiologists are wary of the keto meal plan.
What Are the Possible Cardiovascular Benefits and Risks of the Keto Diet?
The heart’s scourge is inflammation, which injures arteries, says Audrey Fleck, RDN, an integrative and functional nutritionist and certified diabetes care and education specialist in Perkasie, Pennsylvania. “Many times, the cause of inflammation is elevated blood sugar,” she says. What’s more, a keto diet may help lower blood sugar and improve insulin function, and can be anti-inflammatory, she says. Insulin is a hormone that helps regulate blood sugar levels.
One review acknowledged that diet changes are critical for lowering the risk of heart disease. But because of anecdotal reports (e.g., that coworker who swears by keto) and social media, the authors wanted to clear up confusion about the influence of popular diets, including keto, on heart health. The keto diet, they conclude, is effective for weight loss in people who have obesity, and it may lower blood pressure and blood sugar, favorably affect lipid levels, and reduce insulin resistance — in the short term.
However, the study’s authors had major reservations about the fact that saturated fats and animal products are allowed, which are known to increase heart disease risk, and a restrictive diet like keto may prompt people to overconsume these foods. As such, there may be a small set of dieters who would be advised to go on keto: “Therefore, the recommendation to start the ketogenic diet for patients must be made prudently, as this dietary approach will likely not be appropriate for most people. In patients who are meticulous, disciplined, and motivated, the ketogenic diet might be a reasonable approach to employ for cardiovascular disease prevention.”
Indeed, the specific foods you choose on keto matter, too. A 2022 study of over 200,000 men and women who followed a low-carb diet found that those whose diets emphasized animal sources of fat and protein, such as cheese and meat, had a higher risk of developing type 2 diabetes. Those whose diets emphasized vegetable sources of fat and protein, as well as those whose diets deemphasized refined carbs, had a lower risk of developing type 2 diabetes.
A 2021 review examined keto’s effect on the risks of developing several conditions, including cardiovascular disease. It found that a low-carb diet raised levels of LDL cholesterol (LDL-C), commonly called “bad” cholesterol, in about 30 percent of people. In one study included in the review, those following a low-carbohydrate diet had an average LDL-C level increase of 6.2 percent, while those following a conventional low-calorie diet had an average LDL-C level decrease of 11.1 percent. While LDL-C levels usually increased by small to moderate amounts on average, for some people, keto raised their LDL-C levels dramatically, sometimes almost doubling it.
But other research points to the possible cardiovascular benefits of keto. Another study looked at people with type 2 diabetes specifically. One group received standard care, while another was guided in nutritional recommendations to get into ketosis, and they received professional advice for mitigating keto side effects, such as headaches, which could make the experience unpleasant. After one year, while the usual-care group had no changes, those in the ketosis group benefited from reduced cardiovascular risk factors, including decreases in triglycerides, blood pressure, and inflammation, and improved lipid profiles.
There’s a connection between heart disease and diabetes: People with diabetes are about 2 times more likely to have heart disease or stroke than those without the disease, according to the Centers for Disease Control and Prevention (CDC).
Given the conflicting research on keto’s effect on cardiovascular health, it’s important to talk to your doctor about your own risk for heart disease and health history before trying keto, especially if you have diabetes. And while people may lose weight on keto, the key is maintaining that loss, and that’s not a given.
What to Know About Keto if You Want to Help Prevent Heart Disease
There is a lot of talk about the dangers of eating sugar when it comes to your heart. (By “sugar,” we’re talking simple, processed carbs and added sugars.) Indeed, “eating a diet high in sugars can lead to insulin resistance, weight gain, and (down the line) metabolic syndrome,” which increases the risk of heart disease, says Suzanne Steinbaum, DO, a national spokesperson for the Go Red for Women campaign with the American Heart Association in New York City. It was in the ’80s and ’90s that some touted going low or no fat, she says, but then a funny thing happened: “People gained weight [because they were] eating more carbs and sugar.” Today, with the popularity of keto, the pendulum has swung in the other extreme direction, into high fat and very low carb.
If there’s anything to be learned there — and this is what Dr. Steinbaum wants everyone to hear if they’re looking to reduce their risk of heart disease — it’s this: “I promise, there is a place that lies in between low fat and high fat. And that’s a Mediterranean diet filled with good fats like omega-3s from fish and unsaturated fats from avocado and nuts, but also fiber-rich whole grains,” she says.
Warnings About the Keto Diet if You’re at Risk for Heart Disease
If you’re at risk for heart disease (factors include having high blood pressure, high cholesterol, or prediabetes or type 2 diabetes, or if you are overweight or obese, according to the National Heart, Lung, and Blood Institute), one overarching factor to consider is that the keto diet is restrictive, and it’s tough to stick to a restrictive diet, says Steinbaum. “People go on keto and in the short term lose a lot of weight, but it’s not sustainable. So when they go off it, they gain the weight back — and maybe even more,” she says.
Yo-yo dieting can put stress on the heart. One study found that people who have the greatest variability in measures like fasting blood glucose, cholesterol, blood pressure, and body weight are 2.3 times more likely to die from any cause and more than 40 percent more likely to suffer a heart attack or stroke compared with those who stay more stable. Staying stable in these measurements is healthier than constantly going up and down. (Of course, this doesn’t mean that you shouldn’t try to reach a healthy weight, only that restrictive diets that lead to loss and regain can make you worse off than when you began.) “Ultimately what you’re doing [with yo-yo dieting] is setting yourself up for developing metabolic syndrome,” says Steinbaum.
What’s more, lifestyle factors aren’t the only thing that affects your likelihood of developing heart disease. There’s a genetic component, too. Particularly for people with a family history of the disease, genes may affect their ability to metabolize fats. “If you’re one of those people, a keto diet can make the situation significantly worse. This isn’t just about weight loss. It’s about your metabolism on a cellular level, and you can be doing yourself much more harm than good.” Translation: Keto may increase your risk for heart disease if the condition runs in your family.
Is the Keto Diet a Good Choice if You’re Living With Heart Disease?
If you have heart disease, you need to be working closely with your cardiologist to make the best heart-healthy lifestyle changes for you. In terms of your diet, your doctor may recommend the Mediterranean diet — not keto.
A review of over 40 studies found that the Mediterranean diet has strong and consistent cardiovascular benefits: Better conformity with the diet is associated with better cardiovascular health outcomes, including clinically meaningful reductions in rates of heart disease, stroke, and cardiovascular disease.
The authors of another study with similar findings concluded that adding these healthier foods, which include sources of carbs banned on keto — fruit, veggies, legumes, and whole grains — rather than avoiding unhealthy foods (sweets, for instance) was the most important factor in preventing another heart problem.
In an analysis for the American College of Cardiology, which was geared toward an audience of cardiologists, Dariush Mozaffarian, MD, a cardiologist and professor of nutrition at Tufts University in Boston, advised doctors to wade through the trendy diets, including low-carb diets, noting that these have a “minor or uncertain influence on health.” He adds that the Mediterranean diet comes the closest to an evidence-based diet that hits the mark.
The Bottom Line on the Relationship Between Keto and Heart Disease
Heart disease development is based on multiple factors, including blood pressure, cholesterol, blood sugar, family history, smoking, and stress, says Steinbaum. Your diet, while important, “is just a piece of the story,” she says. “Ultimately, it’s not about keto. It’s not about eating sugar. People may want to follow this diet because it makes them feel in control, but nothing is such a quick fix. It’s just not that simple,” she says.
Don’t rely on keto to prevent heart disease or treat existing heart disease. If you’re at risk, go on a keto diet only under the supervision of your doctor or cardiologist, especially if you have a family history of the disease, which, in that case, may mean a keto diet could be dangerous.
Editorial Sources and Fact-Checking
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- Crosby L, Davis B, Joshi S, et al. Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks. Frontiers in Nutrition. July 16, 2021.
- Bhanpuri NH, Hallberg SJ, Williams PT, et al. Cardiovascular Disease Risk Factor Responses to a Type 2 Diabetes Care Model Including Nutritional Ketosis Induced by Sustained Carbohydrate Restriction at 1 Year: An Open Label, Non-Randomized, Controlled Study. Cardiovascular Diabetology. May 1, 2018.
- Diabetes and Your Heart. Centers for Disease Control and Prevention. June 20, 2022.
- Understand Your Risk for Heart Disease. National Heart, Lung, and Blood Institute. March 24, 2022.
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- Mozaffarian D. Diet and Heart Disease — What Every Cardiologist Should Know. American College of Cardiology. May 5, 2016.