Limit refined carbohydrates.

Concentrated sources of sugar like soda and other sweetened drinks, candy, baked goods, jam, and syrup can create radical spikes in your blood sugar — which often leaves you feeling tired a couple of hours later. And although refined, white starch like white bread, crackers, bagels, and rice do not naturally contain sugar compounds, they are metabolized into sugar very quickly and have the same effect. To help lessen volatile blood-sugar swings, limit refined carbs and stick to high–quality ones: vegetables, fruit, whole grains, beans, peas, and lentils.