When it comes to protecting your heart, what you eat matters more than just the amount of carbohydrates or fat on your plate. Recent research underscores that focusing on the quality of foods—choosing whole, minimally processed ingredients—may be far more important than strictly limiting macronutrients like carbs or fats.

Beyond the Low-Carb, Low-Fat Debate

For decades, dietary advice for heart health has often centered around reducing either carbohydrates or fat intake. Popular diet plans promoted low-carb or low-fat approaches as keys to weight loss and cardiovascular disease prevention. But these recommendations sometimes overlook a critical factor: the nutritional value and source of the foods you consume within those diets.

A groundbreaking study led by researchers at Harvard T.H. Chan School of Public Health challenges the idea that simply cutting carbs or fats is enough. Instead, it emphasizes the type of carbs and fats—and the overall quality of the diet—as pivotal in reducing coronary heart disease risk.

The Study That Changed the Perspective

The research team analyzed data from nearly 200,000 participants enrolled in three large U.S. cohort studies: the Health Professionals Follow-Up Study, Nurses’ Health Study, and Nurses’ Health Study II. Over 25 years, they tracked dietary patterns and heart disease outcomes, using detailed food questionnaires to assess not only macronutrient intake but also the healthfulness of foods within those diets.

Their key finding? Low-carb and low-fat diets that prioritize whole grains, fruits, vegetables, nuts, and legumes were linked to about a 15% lower risk of developing coronary heart disease. Conversely, diets low in carbs or fats but high in unhealthy foods—such as refined grains, sugary treats, processed meats, and animal fats—were associated with a higher risk.

Zhiyuan Wu, PhD, lead author of the study, explained that diets rich in plant-based foods improve metabolic function and heart health, whereas unhealthy versions increase heart disease risk, regardless of macronutrient restrictions.

Metabolic Clues: How Diet Quality Affects Your Heart

The study also measured blood metabolites—a variety of biological markers related to metabolism—in over 10,000 participants. This allowed the researchers to see how diet quality influenced factors like lipid profiles and metabolic regulation, both crucial to cardiovascular health.

Interestingly, the findings differentiated between types of low-carb and low-fat diets. For example, “animal-based” low-carb diets, high in saturated fats and animal proteins, correlated with increased heart disease risk. On the other hand, “vegetable-based” low-carb diets showed more favorable effects.

Similarly, unhealthy low-fat diets relying heavily on refined carbs and added sugars raised risk, while diets emphasizing whole, nutrient-dense foods lowered it.

Why Food Quality Matters More Than Macros

Registered dietitian Yaa Boakye explains food quality as the “grading rubric” for your body. “It’s not enough to simply check the box for ‘low carb’ or ‘low fat,’” she says. Instead, it’s crucial to examine what’s actually in your food: fiber content, added sugars, sodium, micronutrients, and inflammatory compounds.

A carbohydrate could be anything from a refined white roll to fiber-rich lentils; a fat could be harmful trans fat or heart-healthy olive oil. Focusing on food quality helps distinguish these vital differences.

Without paying attention to these details, people may meet their macro goals but still consume diets high in sodium, added sugars, and low in essential nutrients like magnesium, potassium, and omega-3 fatty acids—all of which can undermine heart health.

Practical Tips for a Heart-Healthy Plate

Registered dietitian Ayanna Smart recommends a balanced approach to meals. Using the “plate model,” she suggests filling half your plate with vegetables and fruits, one-quarter with lean proteins (such as fish, beans, or low-fat cheese), and one-quarter with whole grains.

This naturally lowers excess carbohydrate and fat intake by cutting down on processed foods and unhealthy fats. Vegetables and fruits provide fiber, vitamins, minerals, and antioxidants that protect your heart and blood vessels, while whole grains help regulate blood sugar—an important factor since poorly controlled blood sugar damages blood vessels and increases heart disease risk.

Lean proteins and nuts contribute healthy fats that maintain good cholesterol levels. Plus, avoiding highly processed foods reduces excess sodium, saturated fat, and calories, helping prevent high blood pressure, atherosclerosis (hardening of arteries), and unwanted weight gain.

The Takeaway: Quality Over Quantity

Ultimately, heart health is less about zeroing in on cutting carbs or fats and more about embracing a nutrient-rich, whole-food diet. Prioritizing minimally processed plant foods, whole grains, and lean proteins while limiting refined grains, added sugars, and unhealthy fats is the most effective path to reducing heart disease risk.

So next time you plan your meals, focus less on the numbers of carbs or fats and more on the quality and source of your food. Your heart will thank you.