Low-Carbohydrate Diets in Korea: Why Does It Matter, and What Is Next?

In recent years, low-carbohydrate diets have become highly popular in Korea as a means to lose weight. People following this regime believe that fat and protein can be consumed in unlimited quantities, as long as carbohydrate intake is strictly restricted. However, low-carbohydrate diets are more complex than simply reducing carbohydrate intake. Meta-analyses of randomized controlled trials revealed that low-carbohydrate diets are at least as effective as low-fat diets in terms of weight loss, but their cardiovascular effects vary. Low-carbohydrate diets confer more beneficial effects on weight loss and lipid profiles such as triglycerides and high-density lipoprotein cholesterol but exhibited detrimental effects on lipid profiles such as total and low-density lipoprotein cholesterol. Korean diets are typically high in carbohydrates, where carbohydrate intake is in the range of 50%–80% of total energy. Within this range of carbohydrate intake, high carbohydrate intake was associated with an increased risk of elevated triglyceride and high-density lipoprotein cholesterol levels but with a reduced risk of elevated total and low-density lipoprotein-cholesterol levels. The optimal range of carbohydrate intake was depicted by a U-shaped relationship between carbohydrate intake and mortality, with 50%–60% of energy from carbohydrates having the lowest mortality risk. The distribution of macronutrients varied greatly according to age and sex groups in Korea. There is no single diet that can be recommended to all individuals, especially if focusing only on the quantity of macronutrients as opposed to their quality. The health benefits of low-carbohydrate or low-fat diets may depend on the source of protein and fat and the carbohydrate quality.