In many parts of the world, food manufacturers are required by law to provide nutritional information on packaged food products. This information is presented in the form of a chart, which can usually be found on the back or side of the package. If you’re curious about what you’re eating, the nutrition facts label is where you should look first. A food’s nutrition facts can tell you everything you need to know about what’s in it, including a comprehensive ingredients list and an overview of each of the major macronutrients. When assessing a food’s nutritional value, you should look at 3 things: protein, carbs, and fat. These macronutrients account for all of the calories in the item (aside from calories from alcohol). As a result, the exact amount of each macronutrient indicates what proportion of the total calories they make up. Alcohol also contains a significant number of calories. Each gram of alcohol is about 7 calories. A gram of protein is estimated to contain about 4 calories. A gram of carbohydrates also has 4, and a gram of fat is worth a whopping 9 calories. If the item you’re eating contains 20g of protein, 35g of carbs, and 15g of fat, this means you would multiply 20x4, 35x4, and 15x9 to find the number of calories contributed by each macronutrient—80, 140, and 135, respectively. Nutrients are always measured in grams. Make sure you’re using the right standard when calculating food calories yourself. Now that you know how the calories are divided up, add together each individual count to get the combined calorie count for one serving of the item. Going off the previous example, 80 + 140 + 135 = 355 calories. This number should correspond with the estimate displayed on the item’s packaging.  Breaking down the calorie count by macronutrient rather than simply reading it off the box allows you to see not just how many calories are in a certain type of food, but how to make them part of a balanced diet. 355 calories might not sound like a lot, but if you’re trying to eat less fat, you might be...

TL;DR in Vietnamese:
Xác định vị trí các thành phần dinh dưỡng trên bao bì. Chú ý lượng đạm, tinh bột và chất béo có trong sản phẩm. Nhân mỗi chất dinh dưỡng đa lượng với lượng calo tương ứng. Tính tổng lượng calo cho mỗi chất dinh dưỡng đa lượng. Tính đến khẩu phần ăn. So sánh lượng calo của các chất dinh dưỡng khác nhau với giá trị được khuyến nghị hàng ngày của chúng.