This is a great question. Counting Calories can be a lot of work. Generally it is not needed once a person understands the concept of not eating concentrated calories.
"Calorie density" is a term that describes a common sense dietary approach that not only ensures excellent nutrition, but also promotes lifelong weight management. When using this approach, we can increase the amount of food on our plates while the caloric content decreases. This optimizes the nutritional value of our meals, aids in satiety, and keeps us from having to go hungry. Counting calories, weighing and measuring portion size is not needed. Jeff Novick explains this concept by stating: "Calorie density is simply a measure of how many calories are in a given weight of food, most often expressed as calories per pound. On a day-to-day basis, people generally eat a similar amount of food, by weight. Therefore, choosing foods with a lower calorie density allows us to consume our usual amount of food (or more) while reducing our caloric intake." This concept is allow referred to on our web sites as the principle of "Concentrated Calories" or "Calorie Concentration."
Here are a blog that might help to answer this question:
Calorie Density = Key to Weight Loss
Here is a little video that might help make this concept understandable:
https://www.youtube.com/watch?v=X6ogG1wEcXo
Sorry for the slow reply. Please feel free to create more discussion
Sean