'Keto-like' diet linked to higher risk of heart disease, new research shows

People who follow a "keto-like" diet of high fat and low carbohydrate foods may be at greater risk for cardiovascular events like heart attacks and strokes, according to a new study.

The study, presented over the weekend at the American College of Cardiology's annual meeting, looked at over 300 participants who reported following a diet consisting of 25% or less of daily calories from carbohydrates and more than 45% of calories from fat.

Compared to the health information of around 1,200 people who eat a standard diet -- with more of a balance between carbs and fat -- the researchers participants on a "keto-like" diet had increased levels of LDL, or "bad" cholesterol, and a higher risk of heart disease.

"To our knowledge, our study is one of the first to examine the association between this type of dietary pattern and cardiovascular outcomes," the study's lead author Dr. Iulia Iatan, 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, said in a statement.

Too much LDL -- or low-density lipoprotein -- cholesterol in the body can cause plaque buildup on the walls of blood vessels, which can cause heart problems like heart disease and stroke, according to the Centers for Disease Control and Prevention. Guidelines from the CDC for lowering high cholesterol include limiting foods high in saturated fat, eating foods high in fiber and low in added sugars and salt.

Low carb diets like the keto diet call for eating foods high in fat and low in carbohydrates.

Keto dieters, for example, drastically cut carbohydrates to about 10% of their daily diet, which in some cases can be just 20 grams of carbohydrates per day.

Foods that are "keto-friendly" include items like meat, eggs, butter, unprocessed cheese, avocados, meat, low-carb veggies and nuts and seeds.

The amount of fat someone following the keto diet may consume in one day could be more than five times the recommended intake for daily fat for the average American, according to Maya Feller, a New York City-based registered dietitian and nutritionist, who was not involved in the study.

The current dietary guidelines for Americans call for eating less than 10% of calories per day from saturated fats, and less than 10% of calories from added sugars, according to the U.S. Department of Agriculture.

Iatan said people who are considering going on a low-carbohydrate, high-fat diet should be aware that the way of eating could increase their LDL cholesterol.

"Before starting this dietary pattern, they should consult a health care provider," she said. "While on the diet, it is recommended they have their cholesterol levels monitored and should try to address other risk factors for heart disease or stroke, such as diabetes, high blood pressure, physical inactivity and smoking."

The study's limitations included that people self-reported that they followed a low-carbohydrate diet, which can be inaccurate. In addition, the study only followed people for a limited amount of time.

The study also only showed a correlation between a low-carbohydrate, high-fat diet and elevated "bad" cholesterol, not a direct link, indicating more research needs to be done.

"There are inter-individual differences in how people respond to this dietary pattern that we don't fully understand yet," said Iatan. "One of our next steps will be to try to identify specific characteristics or genetic markers that can predict how someone will respond to this type of diet."

The ketogenic, keto for short, diet was developed in the 1920s after it was noticed that after fasting, epileptics would experience a marked reduction in their seizures. The diet is designed to get your body into a state called ketosis, when your body is so low on carbohydrates it starts burning fat for fuel.

Ketosis is also what the body does when fasting.

The diet's proponents say it is the best way to lose weight without feeling hungry and that it increases energy levels. Some studies have found that following a "keto-like" diet can help with weight loss, which leads to improved health benefits, including increased "good" cholesterol.

A study presented at the American College of Cardiology's annual meeting in 2019 found that people on low-carb diets were more likely to develop atrial fibrillation, a common heart rhythm disorder, than people on a moderate-carb diet.