The term carb is simply an abbreviation for carbohydrate, which includes sugars, starches and fibers. The bok choy vegetable is low in carbohydrates. According to the USDA, a cup of raw bok choy contains 1.5 grams of carbohydrates. Some people limit the number of carbs they consume for various reasons, such as when they are trying to lose weight or adhere to a specific diet for health reasons.