What is food exchange portion: It means that commonly used foods are categorized according to the characteristics of their nutrients, and then one portion is designated as one portion in each category of food according to the commonly used amount, and the rough nutrient content (protein, fat, sugar, energy) of each portion of food is calculated, and then the amount of food with equivalent nutrients is calculated for the rest of the food in each category of food. For example, 50 grams of lean pork = 50 grams of lean beef (70 grams of ribs with bones / 60 grams of eggs / 80 grams of grass carp / 200 grams of tofu, etc.). We refer to the calculated value of each of these foods as a serving, and they can be directly exchanged as a serving when making recipe choices. This ensures that we are eating similar calories and variety every day. What is the energy density of a food: Energy density refers to the amount of energy per gram of food, which is closely related to the moisture and fat content of the food. Foods with a high water content have a low energy density, while foods with a high fat content have a high energy density. People in the eating process to produce a sense of fullness depends mainly on the weight of the food intake, and eat high-fat, high-calorie food will obviously eat the same weight of fruits and vegetables than the intake of more calories, to give a simple example: a beef burger contains calories, can be worth a whole bunch of carrots. We may not be able to eat that pile of carrots in a day, but we can easily eliminate a burger. That’s why we need to eat more vegetables and fruits.