By Dr. Bhupinder Singh and Dr. Sanjay Kalra
In an era flooded with diet trends—low-carb, keto, low-fat—the message from science is getting clearer: it’s not just what diet you follow, but the quality of the food you eat that truly matters for your heart.
A groundbreaking study presented at NUTRITION 2025, the annual meeting of the American Society for Nutrition held recently in Orlando, has revealed that people who focus on high-quality foods—whether on a low-carb or low-fat diet—significantly reduce their risk of coronary heart disease (CHD).
Led by Zhiyuan Wu and a team from the Harvard T.H. Chan School of Public Health, the research analyzed dietary patterns and health outcomes of nearly 200,000 people over several decades. The results? A healthy low-carb or low-fat diet can reduce CHD risk by up to 15%, but only when those diets are rich in whole grains, fruits, vegetables, nuts, and legumes.
What Makes a Diet “Healthy”? It’s the Ingredients.
The study divided foods into two broad categories:
- High-quality (Healthy): Whole grains, fresh fruits and vegetables, legumes, nuts, and plant-based proteins.
- Low-quality (Unhealthy): Refined grains, processed meats, sugary drinks, potatoes, and saturated fats from animal sources.
Participants who followed plant-based, minimally processed diets—regardless of whether they were low in carbs or fats—had significantly lower CHD risk.
In contrast, those who consumed animal-based and processed food-heavy diets had an increased risk of developing heart disease, even if their carb or fat intake was technically “low.”
Inside the Numbers: The Largest Study of Its Kind
The study drew data from three massive long-term surveys:
- Health Professionals Follow-Up Study (43,430 men, 1986–2016)
- Nurses’ Health Study (64,164 women, 1986–2018)
- Nurses’ Health Study II (92,189 women, 1991–2019)
Over 5.2 million person-years of follow-up, researchers documented 19,407 CHD cases. They created multiple indices to classify diet patterns—five for low-carb diets and three for low-fat diets—based on the source and quality of macronutrients.
The findings were consistent:
- Healthy Low-Carb Diet: 6% reduced risk (aHR 0.94)
- Unhealthy Low-Carb Diet: 5% increased risk (aHR 1.05)
- Healthy Low-Fat Diet: 6% reduced risk (aHR 0.94)
- Unhealthy Low-Fat Diet: 4% increased risk (aHR 1.04)
Even more interestingly, the researchers used plasma metabolomics to identify how these diets altered key blood markers. The healthier the food choices, the more favorable the biomarker profiles.
The Bottom Line: Don’t Just Eat Less—Eat Smarter
This landmark study sends a powerful message to the public, clinicians, and policymakers alike:
“Focusing on food quality is more important than obsessing over macronutrient labels.”
In simple terms, you can follow a low-carb or low-fat diet and still be unhealthy if you’re loading up on processed and refined foods. But swap those out for plant-based, minimally processed items, and you can dramatically reduce your risk of heart disease.
Heart-Healthy Habits You Can Start Today
- ✅ Fill half your plate with vegetables and fruits
- ✅ Choose whole grains over refined ones
- ✅ Snack on nuts instead of chips
- ✅ Replace red meat with plant proteins like beans or lentils
- ✅ Read food labels to avoid hidden sugars and saturated fats
- ❌ Limit processed meats, sugary drinks, and fried foods
Whether you’re going low-carb, low-fat, or anything in between, the real key to heart health lies in the quality of your choices. The latest research confirms: your heart doesn’t care about the label—it cares about the nutrients.
Reference
1. Zhiyuan Wu, et al. (P17-077-25) Low-carbohydrate and low-fat diets, objective biomarker indices, and coronary heart disease in US men and women. June 1, 2025. Available at: https://nutrition2025.eventscribe.net/index.asp?posterTarget=728431.