Key to Heart Health Isn’t Cutting Carbs or Fat

For quite some time, the nutrition community has had differing opinions about which diets are best for maintaining a healthy heart. Some say low-carbohydrate diets are best for heart health, while others support low-fat diets.

Now, researchers at the Harvard T.H. Chan School of Public Health in Boston have shared their thoughts on those opinions. A massive study by the investigators suggests that whether a low-carb or low-fat diet is effective in reducing heart disease risk depends more on the quality of the food itself rather than on the amount of carbohydrates or fat consumed.

Additionally, the researchers discovered that both low-carb and low-fat diets built from healthy whole-food sources were associated with reducing the risk of coronary heart disease (CHD). The study also noted that versions of either diet that are “unhealthy” because they are high in refined grains and animal proteins actually increase the risk of CHD.

CHD the most common type of heart disease and the leading cause of death in the United States, according to the National Heart, Lung, and Blood Institute. CHD occurs when the arteries of the heart can’t supply enough oxygen-rich blood to the heart muscle because of narrowing from the buildup of fatty deposits, known as plaque.

“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,” Zhiyuan Wu, lead author of the study and a postdoctoral research fellow at the Harvard T.H. Chan School of Public Health, said in a news release.

“The efficacy of low-carb and low-fat diets in reducing CHD risk is a topic of ongoing debate, and past studies showed mixed findings.”

According to Wu, one reason for these conflicting findings may be that some past studies didn’t distinguish between a “healthy” low-carb diet, such as one rich in vegetables and nuts, and an “unhealthy” one, with foods like bacon and butter, which are high in saturated fats.

“Focusing only on nutrient compositions but not food quality may not lead to health benefits,” Wu said in the news release.

However, there have been studies that have shown that diets rich in healthy sources of carbohydrates and fats—such as whole grains, fruits, vegetables, nuts, legumes, and olive oil—are linked to a reduced risk of CHD.

The Harvard researchers wanted to examine this evidence, particularly regarding low-carb and low-fat diets. To do this, the team followed nearly 200,000 adults in the United States for more than 30 years. The long-term study, published in the Journal of the American College of Cardiology, allowed the investigators to see how different eating patterns affected CHD risk as people aged.

The investigators followed participants from three large long-term studies from 1986 to 2019 to determine how many developed CHD. The studies were the Nurses’ Health Study (NHS), NHS II, and Health Professionals Follow-up Study. The total number of participants was 42,720 men and more than 155,000 women. A total of 20,033 cases of CHD were documented during the study.

Diet patterns were evaluated through food frequency questionnaires, and indices were developed to identify healthy and unhealthy low-carbohydrate and low-fat diets based on food sources and macronutrient quality.

Among the key findings of the study that the research team noted were:

• Unhealthy low-carb and low-fat diets high in refined carbohydrates and animal-based fats and proteins were associated with a higher risk of CHD.

• Healthy dietary patterns were linked to lower triglycerides, higher HDL cholesterol, and reduced inflammation.

“These results suggest that healthy low-carbohydrate and low-fat diets may share common biological pathways that improve cardiovascular health,” Wu said in the press release. “Focusing on overall diet quality may offer flexibility for individuals to choose eating patterns that align with their preferences while still supporting heart health.”

Wu added that nutritional counseling should prioritize diet quality over merely limiting carbohydrates or fats.

Tips to Establish a Heart-Healthy Diet

If you’re looking to improve your diet for better heart health, consider these practical tips provided by Verywell Health:

Focus on eating whole, minimally processed foods. Regardless of whether you prefer a low-carb diet or a low-fat diet, focusing on nutrient-rich foods is essential for heart health.

• Cut back on ultra-processed and refined foods. Fat-free “diet” snacks and refined grains may be low in fat and calories, but that doesn’t mean they are heart-healthy.

• Opt for unsaturated fats instead of saturated fats. Replace saturated fats found in animal products, coconut oil, and palm oil with healthier options such as olive oil, avocados, and nuts.

• Focus on the quality of food, not just macronutrient counts. Instead of worrying about carb or fat gram counts, prioritize the quality and source of what you’re eating.

• Find a sustainable routine that fits your life. Because there’s no single “best” macronutrient ratio, choose a plan based on high-quality, wholesome foods that you can realistically maintain.

If you want personalized advice on heart-healthy foods, it’s a great idea to talk with a dietitian who can create a diet plan that’s just right for you and takes your health into account.

Source Links:

https://www.verywellhealth.com/key-to-heart-health-11990306
https://www.acc.org/about-acc/press-releases/2026/02/11/18/16/healthy-versions-of-low-carb-and-low-fat-diets-linked-to-better-cardiovascular-and-metabolic-health
https://hsph.harvard.edu/news/low-carb-and-low-fat-diets-associated-with-lower-heart-disease-risk-if-rich-in-high-quality-plant-based-foods-low-in-animal-products/