“Keto-like” diets may increase your risk of heart disease, according to new expert research

Low-carb, high-fat diets may actually be more dangerous than beneficial as they increase "bad" cholesterol

By Joy Saha

Staff Writer

Published March 12, 2023 4:30PM (EDT)

Breakfast of fried eggs and bacon (iStock / Getty Images)
Breakfast of fried eggs and bacon (iStock / Getty Images)

"Keto-like" diets, which prioritize fat consumption over protein and carbohydrates, may double the risk of cardiovascular diseases such as blocked arteries, heart attacks and strokes, according to a new study.

Led by Dr. Iulia Iatan — an attending physician-scientist at the Healthy Heart Program Prevention Clinic, St. Paul's Hospital and University of British Columbia's Centre for Heart Lung Innovation in Vancouver, Canada — the study looked at how low-carb, high-fat (LCHF) diets, similar to the uber-trendy keto diet, may be linked to higher levels of "bad" cholesterol.

"Our study found that regular consumption of a self-reported diet low in carbohydrates and high in fat was associated with increased levels of LDL cholesterol — or 'bad' cholesterol — and a higher risk of heart disease," Iatan said in a news release, per CNN.

Specifically, researchers in the study defined a low-carb, high-fat diet as 45% of total daily calories coming from fat and 25% coming from carbohydrates. Data was obtained from two distinct groups — one with 305 individuals eating a LCHF diet and another with 1,200 individuals eating a standard diet — using the United Kingdom database UK biobank over the course of at least a decade. Those who followed the LCHF diet had higher levels of LDL (low-density lipoprotein) cholesterol along with apolipoprotein B (apoB), which attaches to the former and carries it through the body.

High amounts of LDL (low-density lipoprotein) cholesterol can lead to build ups or "plaque" on the walls of blood vessels, which, in turn, can cause both heart disease and stroke. LDL paired with triglycerides, a type of fat that the body uses for energy, can further increase the risks.

"After an average of 11.8 years of follow-up — and after adjustment for other risk factors for heart disease, such as diabetes, high blood pressure, obesity and smoking — people on an LCHF diet had more than two-times higher risk of having several major cardiovascular events, such as blockages in the arteries that needed to be opened with stenting procedures, heart attack, stroke and peripheral arterial disease," researchers found.

They also noted that those following a LCHF diet had double the consumption of animal sources compared to those following a standard diet — 33% compared to 16%.

While the study includes important findings, it has a few limitations, including "measurement errors that occur when dietary assessments are self-reported" and a small sample size, Iatan said, per CNN. The study's participants were also all mostly British.  

The study, which was presented Sunday at the American College of Cardiology's Annual Scientific Session Together With the World Congress of Cardiology, has not been peer reviewed at this time. Researchers asserted that their study was purely observational and "can only show an association between the diet and an increased risk for major cardiac events, not a causal relationship." They added that further studies are necessary, "especially when approximately 1 in 5 Americans report being on a low-carb, keto-like or full keto diet."

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Ketogenic "keto" diets originated in the 1920s to help manage seizures in children with epilepsy. In recent years, the diet rose to popularity as a kind-of "fad" diet to help promote weight loss. The crux of a keto diet is ketosis, which is "a metabolic adaptation to allow the body to survive in a period of famine," per dieticians from the University of Chicago Medicine. Instead of breaking down sugar or glucose from carbohydrates, the body breaks down stored fat for energy.

To achieve ketosis, one must eat 75 to 90% of their daily calories from fat, 5% of calories from carbohydrates and 15% of calories from protein. That being said, nutritionists recommend people prioritize healthy fats, like dairy, oils and nuts, rather than animal fats. 

"Red meat and full fat dairy elevates LDL cholesterol and should be eaten in moderation. For a healthy heart, people should limit the keto diet," said nutrition consultant, author and professor Dr. Lisa Young. "A healthier version of a low-carb diet would include more fish instead of red meat and include healthy fats like nuts, seeds, and olive oil."

As with all diets, it's important to keep in mind that the keto diet can cause low blood pressure, kidney stones, constipation, nutrient deficiencies and an increased risk of heart disease. Those with pre-existing health conditions should avoid going keto the research shows it may be incredibly unsafe.

By Joy Saha

Joy Saha is a staff writer at Salon. She writes about food news and trends and their intersection with culture. She holds a BA in journalism from the University of Maryland, College Park.


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Cardiovascular Diseases Food Heart Disease Keto Diet