It’s Not About Low-Carb or Low-Fat—It’s What’s On Your Plate

Study of 200,000 people finds diet quality, not just macronutrients, protects the heart

Orlando, FL — A landmark study presented at Nutrition 2025 has followed nearly 200,000 people for decades and reached a game-changing conclusion: the quality of the food matters more than whether you follow a low-carb or low-fat diet when it comes to heart health.

“What you eat on a low-carb or low-fat diet matters just as much as the diet itself,” said Dr. Zhiyuan Wu of Harvard T.H. Chan School of Public Health.

The research showed that low-carbohydrate or low-fat diets rich in whole grains, fruits, vegetables, legumes, and nuts were consistently associated with a significantly lower risk of coronary heart disease—by about 15%. On the other hand, versions of those diets loaded with processed foods, refined carbs, or animal-based fats were linked to worse outcomes.

To further validate their findings, the researchers analyzed blood metabolites in over 10,000 participants to see how healthy vs. unhealthy food choices affected metabolism.

“Improving food quality is key to improving heart health,” Wu emphasized.

This study underscores a critical shift in nutrition science: macros alone don’t define a healthy diet. Instead, it’s about building your plate with nutrient-dense, unprocessed, plant-forward foods—and avoiding sugar-laden, packaged, or heavily refined options.

Researchers plan to continue their work by investigating how genetics, lifestyle, and additional metabolic markers may influence diet outcomes, potentially leading to more personalized and effective dietary recommendations in the future.