How are food calories calculated?

The calculation of food calories is mainly achieved by analyzing its nutritional components. Specifically, the three major nutrients in food—carbohydrates, fats, and proteins—each have different energy values. Typically, 1 gram of carbohydrates and proteins produces 4 kilocalories (kcal) of energy, whereas 1 gram of fat produces 9 kilocalories. To calculate the caloric content of food, the grams of each nutrient in the food are multiplied by their respective energy values, and then these energy values are summed. For example, if a certain food contains 10 grams of carbohydrates, 5 grams of fat, and 8 grams of protein, then its caloric content would be calculated as follows: 10g × 4 kcal/g + 5g × 9 kcal/g + 8g × 4 kcal/g = 121 kcal. This method of calculation helps in understanding the specific energy content of food, thus aiding in dietary control, maintaining a healthy weight, and achieving energy balance.