Question: What is the energy density of foods and why is it important?
Answer: The energy density of food refers to the calorie content per weight of food. We know that we tend to consume a fairly consistent weight of food from day to day. But some foods have more calories, more energy per weight, than others do. One component that might influence energy density for instance would be the water content of food. And a salad for instance, is a meal of relatively low energy density because there's a lot of water in the vegetables that comprise a salad. A pretzel may be a fairly high energy density food because there's obviously little if any water content to a pretzel so you're getting -- per weight unit -- you're getting more calories.
This is important in weight management because if we understand that we do tend to consume a fairly consistent amount of food, weight-wise. If that amount of food contains less calories, obviously we'll be consuming a lower calorie diet, and research has shown that people are able to actually lose weight without feeling deprived if they emphasize foods of lower energy density in their diet.