A decade-long study of nearly 200,000 adults examined the impact of eating habits on heart health. Both low-carb and low-fat diets were associated with a lower risk of heart disease if they emphasized whole grains, plant-based foods, and healthy fats. Conversely, diets rich in refined carbohydrates and animal fats increased the risk of heart disease. Food quality, not quantity, is key to heart health, according to a study. The study thus calls into question the long-standing debate about low-carbohydrate versus low-fat diets.