For years, nutrition debates have focused on whether low-carb or low-fat diets are best. But a major new study suggests that what you put on your plate matters far more than what kind of diet you claim to follow.
Researchers at Harvard T.H. Chan School of Public Health tracked nearly 200,000 people over several decades and found that heart disease risk dropped significantly for those who focused on eating high-quality foods, regardless of whether their diet was low-fat or low-carb.
The key? Choosing minimally processed, plant-based foods like whole grains, vegetables, nuts and legumes, while limiting refined carbs, sugary foods and processed meats.
“We found that what you eat on low-carb or low-fat diets matters just as much as the diet itself,” said Zhiyuan Wu, PhD, the study’s lead author. “Healthy versions of these diets — those rich in plant-based foods and whole grains — were linked to better heart health outcomes.”
The study, presented at the American Society for Nutrition’s NUTRITION 2025 conference, included data from three large, long-term health studies and even analyzed blood markers in over 10,000 participants to assess how diet impacted metabolic function.
People who followed a high-quality low-carb or low-fat diet were about 15% less likely to develop coronary heart disease. But those who followed low-carb or low-fat diets built on low-quality foods — like white bread, sugary snacks and red or processed meat — actually faced a higher risk of heart disease.
The bottom line: diet labels matter less than food quality. For better heart health, aim to build your meals from whole foods and plants, not packages.
This research was supported by grants from the National Institutes of Health.