Nutrient density is a measure of the nutrients a food provides compared to the calories it provides. Foods low in calories and high in nutrients are nutrient dense, while foods high in calories and low in nutrients are nutrient poor. Nutrient-dense foods should be eaten often, whereas nutrient-poor foods should only be eaten occasionally. A healthful diet includes mostly nutrient-dense foods. People who restrict their calories should obtain as much nutrition as they can from the calories they consume by choosing nutrient-dense foods. Those who consistently choose nutrient-poor foods will not get the nutrients they need.