When it comes to carbohydrates, we appear to have more proof that quality matters more than quantity. To assess the impact that the carbohydrate quality index (CQI) has on heart health, Spanish researchers collected dietary intake data from 5,373 adults, ages 55–75, involved in a lifestyle weight-loss program. All subjects were overweight or had obesity.

The researchers tracked 6- and 12-month changes in CQI, such as increases in dietary fiber intake and improvements in the ratio of whole-grain to total-grain consumption. The scientists also measured markers that play a role in cardiovascular health (e.g., blood pressure and blood cholesterol). In the end, most people improved their CQI by eating more high-quality carbs—substituting foods like whole grains, fruits and legumes for lesser-quality options like refined cereals and sugar-sweetened drinks—without necessarily eating fewer carbs overall. With these changes, a wide range of health measures associated with heart disease improved, including waist circumference, triglyceride levels and fasting blood sugar.