Reason 1: Carbs can help boost your mood.Researchers suspect that carbs promote the production of serotonin, a feel-good brain chemical. In a study from the Archives of Internal Medicine, people who followed a very low carbohydrate diet for a year—which allowed only 20 to 40 grams of carbs daily, about the amount in just 1⁄2 cup of rice plus one piece of bread—experienced more depression, anxiety and anger than those assigned to a low-fat, high-carb diet that focused on low-fat dairy, whole grains, fruit and beans.