LOW-CARB OR LOW-FAT? THE RIGHT FOODS MATTER MORE FOR HEART HEALTH, STUDY FINDS

Fact checked by Nick Blackmer

• New research suggests that diets low-fat and low-carbohydrate diets may lower heart disease risk.
• However, only diets low in refined carbs and animal products and rich in plant-based foods reduced risk.
• The findings shift the conversation around these diets from quantity to quality, experts said.

A new study suggests that when it comes to low-carbohydrate or low-fat diets, the quality of the foods you choose may matter more for heart health than the amount of carbs and fats you consume. The research, published in February in the Journal of the American College of Cardiology, specifically found that diets low in refined carbohydrates and animal products but rich in plant-based foods were associated with a lower risk of heart disease.

The findings suggest the long-running debate over which diet is better may have overlooked a more important question, said Carlos Macias, MD, a cardiac electrophysiologist at UCLA Health who was not involved in the research. “In the past, there was probably too much focus on the label ‘low-carb’ or ‘low-fat’ without asking what people were actually eating,” he said.

Analyzing Eating Patterns

To assess how these diets may influence heart health, researchers followed nearly 200,000 participants—mostly healthcare professionals—enrolled in three long-running studies. After more than 30 years of follow-up, about 20,000 participants developed coronary heart disease. 

Using self-reported dietary data, blood samples, and health records, researchers evaluated how the body responds to different versions of low-carbohydrate and low-fat diets—and how those patterns relate to the risk of developing coronary heart disease, said lead study author Zhiyuan Wu, PhD, a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health.

Quality Over Quantity

Diets centered on high-quality carbs, like whole grains and legumes, and plant-based sources of fats and protein were associated with a roughly 15% lower risk of coronary heart disease. On the flip side, low-fat and low-carb diets high in animal protein and refined carbohydrates, including foods like white bread and pasta, were linked to a higher risk.

People who followed higher quality versions of low-carb or low-fat diets also showed higher levels of high-density lipoprotein (HDL), or “good cholesterol,” and lower levels of triglycerides, a type of fat in the blood that can raise the risk of heart disease and stroke. 

These findings suggest that “an overall healthy eating pattern emphasizing macronutrients from whole grain, high quality plant-based foods is the key strategy for the primary prevention of heart disease,” Wu said.

Still, the study comes with important caveats. Because it was observational, researchers could show links between certain eating patterns and health outcomes, but they couldn't prove cause and effect. Participants also self-reported their diets, which leaved room for inaccuracies. And since most participants were health care professionals, the findings may not fully apply to the broader public, where more extreme dietary patterns may be common.

Even with these caveats, though, Macias said the study “clears up a lot of confusion from past debates.” It indicates that both low-carb and low-fat diets can either help or harm cardiovascular health depending on what people are eating. In short, he added, it “really shifts the conversation toward quality over quantity.”

Read the original article on Health

2026-03-09T14:05:27Z