Final answer:
Calories per gram is a measure of the energy a food provides relative to its weight. It is calculated by multiplying the number of grams of protein, carbohydrates, and fats in the food by their respective caloric values and summing them up. The caloric content of foods is determined using bomb calorimetry.
Step-by-step explanation:
Calories per gram is a measure of the energy a food provides relative to its weight. It is calculated by multiplying the number of grams of protein, carbohydrates, and fats in the food by their respective caloric values and summing them up. For example, if a food contains 5 grams of protein, 31 grams of carbohydrates, and 12 grams of fat, you multiply 5 by 4 (calories per gram of protein), 31 by 4 (calories per gram of carbohydrates), and 12 by 9 (calories per gram of fat), and then sum the results to get the total energy in calories.
The caloric content of foods is determined using a method called bomb calorimetry. This involves burning the food and measuring the energy released. The values on food labels are derived from the average caloric content of the different chemical constituents of food, based on bomb calorimetry results.