What is the concept of nutrient density and calorie control addressed

In their view also, the nutrient-to-calorie ratios provide a more direct comparison between the intake of essential nutrients and the amount of energy that the food provides. The nutrient density concept is most useful when energy intake is low and it is essen- tial that nutrient-rich foods be included in the diet.

cutting out negative people, changing their diets, exercising, taking off days from work or school, etc