Key TakeawaysFocusing on high-quality, plant-based ingredients can protect the heartDiets high in refined sugars and animal products increase heart disease risk regardless of fat or carb countsHealthy eating patterns lower inflammation and improve cholesterol levels, leading to better long-term metabolic health.FRIDAY, Feb. 13, 2026 (HealthDay News) — For years, the world of nutrition has been a battlefield between two camps: Those who swear by low-carb living and those who stick to low-fat diets.But a massive new study suggests that the winner of this debate isn't a specific macronutrient ratio, but rather the quality of the food on your plate.Researchers at the Harvard T.H. Chan School of Public Health in Boston found that both low-carbohydrate and low-fat diets can significantly reduce the risk of coronary heart disease (CHD) — provided they are built from healthy, whole-food sources.Conversely, "unhealthy" versions of either diet, packed with refined grains and animal proteins, actually increased health risks.The study — published Feb. 11 in the Journal of the American College of Cardiology — followed more than 198,000 U.S. adults for more than 30 years. This long-term perspective allowed scientists to see how different eating patterns affected heart health over a lifetime.“Our findings highlighted that it’s not simply about cutting carbs or fat, but it’s about the quality of foods people choose to construct those diets,” lead author Zhiyuan Wu, a postdoctoral research fellow, said in a news release.Wu noted that past studies often produced conflicting results because they didn't distinguish between a "healthy" low-carb diet (full of vegetables and nuts) and an "unhealthy" one (heavy on bacon and butter). As it turns out, “focusing only on nutrient compositions but not food quality may not lead to health benefits,” Wu added.For example, the study showed that the "unhealthy" low carb dieters had a 14% greater risk of CHD, and the "healthy" low carb dieters had a 15% lower risk of CHD.To understand why quality matters so much, researchers looked at metabolomic profiles — the tiny chemical fingerprints left behind by the body’s natural processes.Healthy versions of both diets, which emphasized plant-based foods, whole grains and unsaturated fats, were linked to:Lower triglycerides (fats in the blood)Higher HDL "good" cholesterolReduced levels of inflammationIn contrast, diets high in refined carbohydrates (like white bread and sugary snacks) and animal-based fats showed unfavorable biomarker profiles that contribute to clogged arteries.“The findings show that what matters most for heart health is the quality of the foods people eat," said Dr. Harlan Krumholz, the journal’s editor-in-chief. "Whether a diet is lower in carbohydrates or fat, emphasizing plant-based foods, whole grains and healthy fats is associated with better cardiovascular outcomes.”More informationThe National Institutes of Health offers more guidance on heart-healthy eating patterns and nutrition.SOURCES: American College of Cardiology, news release, Feb. 11, 2026; Journal of the American College of Cardiology, Feb. 11, 2026 .What This Means For YouRather than counting grams of fat or carbs, focus on replacing refined starches and processed meats with whole grains, beans, nuts and healthy oils..Sign up for our weekly HealthDay newsletter