Dietary carbohydrate quality may play an important role in disease development. We evaluated the association between carbohydrate quality index (CQI) and the prevalence of obesity and metabolic disorders among adults in South Korea.

We analysed 12 027 adults aged 19–64 years from the fifth Korea National Health and Nutrition Examination Survey (KNHANES). CQI was based on four criteria: crude fibre intake, dietary glycaemic index (DGI), whole grains/total grains ratio and solid carbohydrates/total carbohydrates ratio.

Participants with a lower CQI were younger, had a lower income and were more likely to be smokers and to drink alcohol. The highest quintile CQI group showed the lowest DGI and the lowest consumption of liquid carbohydrates and refined grains, as well as the highest consumption of solid carbohydrates, crude fibre and whole grains (P < 0.05). A higher CQI was negatively associated with the prevalence of obesity (odds ratio = 0.83; 95% confidence interval = 0.69–0.99) and hypertension (odds ratio = 0.78; 95% confidence interval = 0.61–0.99) but was not associated with other metabolic disorders.

These results suggest that the quality of carbohydrates consumed is associated with the risk of obesity and hypertension. However, the cross‐sectional design does not preclude reverse causality.