Summarize:

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 alarmed to discover that fat grams account for nearly half of the total. Be aware that the figures for both the calories and macronutrients represented in the nutritional facts only indicate a single recommended serving. If there are multiple servings included in the package, the total number of calories will actually be much higher. This can be an important fact to keep in mind if you’re tracking calories as part of a diet or exercise plan. For example, an item containing 355 calories per serving and with 3 servings per package makes the total 1,065 calories. According to dietitians and other food experts, 46-65% of the total calories you consume on a daily basis should come from carbohydrates, 10-35% from protein, and 20-25% from fats. The recommended daily value (DV) column featured in the nutrition facts will tell you how much of those proportions you’re getting from the item.  A snack containing 35g of carbohydrates, for instance, provides roughly 12% of your recommended daily value of around 300g.  Daily values are averages based on dietary recommendations for adults who eat around 2,000 calories a day.
Locate the nutrition facts on the item’s packaging. Note the amount of protein, carbohydrates, and fat contained in the item. Multiply each macronutrient by its caloric equivalent. Total the calories for each macronutrient. Take serving size into account. Compare the calories of different nutrients to their recommended daily values.