Thinking about the nutrient density of the food is another conceptual way of making sensible food decisions. The nutrient density of a food can be thought of as the amount of nutritional value, including vitamins, minerals, and fiber, divided by the calories, or energy content, of that food. For example, a glass of soda is high in calories without providing much in the way of nutritional value. Foods that provide lots of calories with very little nutritional value are sometimes called energy dense foods, but their nutrient density is low. A bunch of fresh spinach, on the other hand, would be an example of a nutrient dense food because its nutritional value is relatively high compared to its caloric content. When people talk about fast food being cheaper than fresh food, they're often referring to the fact that the cost per calorie of highly processed food is lower than that of fresh, whole food. This is often true because highly processed food is so high in calories that the cost per calorie is relatively low. But, if we instead look at the cost of food per unit of nutrient density, then buying fewer calories of higher nutrient density food is a much better use of our food budget.