A new study has found that Keto-like diets that are high in fat and low in carbohydrates could actually double the risk of cardiovascular issues, like chest pain (angina), blocked arteries needing stents (tiny coils that open blocked arteries), heart attacks and strokes.
These findings, which suggest that a keto-style eating plan can lead to increased levels of low-density lipoprotein (LDL) or “bad” cholesterol, were presented at the American College of Cardiology’s Annual Scientific Session. In turn, these high levels of cholesterol could also heighten the risk of cardiovascular disease.
Senior study author and associate professor in the Department of Medicine at the University of British Columbia in Canada, Liam Burnham, MD, who is also the medical lead with the Healthy Heart Program Prevention Clinic at St. Paul’s Hospital in Vancouver, said “If you are following a carbohydrate-restricted diet, our data suggest that it may be important to monitor your cholesterol levels.”
Dr. Brunham adds, “If cholesterol levels are super high, consult with your doctor because there may really need to be careful attention paid to managing the risk of heart disease.”
In order to conduct the study, which is considered preliminary since it has yet to be reviewed by peers for publication in a medical journal, Dr. Brunham and his research team looked at information from over 70,000 people within the United Kingdom who had completed a ‘one-time, self-reported, 24-hour diet questionnaire.’ The researchers also drew their blood at the same time to check on the participants’ cholesterol levels.
As for the questionnaire responses, at least 305 of the participants said that they followed a low-carbohydrate, high-fat diet.
How Keto-Like (Low-Carb, High-Fat) Diets Work
For diets that follow Keto-like rules, people restrict their intake of carbohydrates, such as those found in foods like bread, pasta, baked goods, and particular fruits and vegetables, as well as proteins, the body ends up using its own reserves for “fuel.” As a result, chemicals called ketones are produced, which is what the body then uses as energy. This process, called ketosis, which burns stored fat, is what helps people lose weight.
According to the International Food Information Council, in 2020, around 8 percent of Americans were on a ketogenic diet.
The Harvard T.H. Chan School of Public Health says that for people following a strict ketogenic diet, they’ll usually get around 70 to 80 percent of their daily calories from fat, 5 to 10 percent from carbohydrates, and 10 to 20 percent from protein. To have enough participants to make proper conclusions, the Canadian researchers searched for people following a keto-like diet that included more than 45 percent of daily calories from fat and 25 percent or less from carbs.
As for the 305 subjects eating a low-carbohydrate, high-fat diet, they were matched with 1,220 individuals who claimed to eat a standard diet that consisted of a bit over 50 percent of daily calories from carbs and almost 31 percent from fat.
For both the keto and standard groups, around three-quarters were women whose average age was 54.
Keto Group Had Higher LDL and More Heart Trouble
On average, after nearly 12 years of follow-up, the participants on the keto-like diet had more than double the risk of having several major cardiovascular events, such as blockages in the arteries that needed stents, or heart attacks, stroke, and peripheral arterial disease. The study also showed that in all, ‘9.8 percent in the low-carbohydrate, high-fat group experienced a new cardiac event, compared with 4.3 percent on a standard diet. ‘
In contrast to those on a standard diet, those on a low-carbohydrate, high-fat diet had much higher levels of both LDL cholesterol and apolipoprotein B (apoB), which is a protein found on the surface of cholesterol. As per the study research, this could be a more accurate indicator of cardiovascular risk than LDL alone.
When the researchers looked at the percentage of people in each dietary group that could be defined as having major high cholesterol, the research group recorded 5 percent in the standard group versus almost 10 percent in the low-carb, high-fat group.
“Probably the diet in which there’s a large consumption of saturated fats from animal products is likely contributing to the increase in cholesterol,” says Dr. Brunham.
Looking At the Connection Between LDL Cholesterol and Heart Disease
Nutrition scientist and professor of medicine at Stanford School of Medicine, Christopher Gardner, PhD, who has previously published research on the effects of low-fat, low-carbohydrate diets but wasn’t part of the study shares that he wasn’t surprised by the keto study results.
He shared, “My division chief is a preventive cardiologist. He sees this all the time — people coming in saying they are on keto, and their LDL cholesterol is through the roof.”
“Every time you’re on a keto diet, you have high saturated fat and low fiber — there’s no other way to do it. So LDL goes up,” he adds.
The Centers for Disease Control and Prevention describe it as ‘too much LDL in the body can lead to a buildup of plaque in the blood vessels, causing them to become narrowed or blocked.’
When it comes to the study limitations, Dr. Gardner also says that the investigation was based on a single, 24-hour dietary report. And while the research shows increased risks from keto-like diets, it doesn’t necessarily prove that the diet itself is what causes these kinds of outcomes.
However, he finds the conclusions of the researchers a bit concerning, saying, “If you’re going to try a ketogenic diet, you should do it under physician supervision so they can see what’s happening to your LDL cholesterol.”
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