When you are eating foods that come in a bag or a box, it's not too difficult to count food calories, but if you are dining at a restaurant, or eating fresh, whole foods from the grocery store or farmer's market, it takes a bit of effort. Packaged foods have to have modern nutrition labels detailing all the calorie and macronutrient information for the food, but prepared foods served in a restaurant or foods sold fresh or in bulk do not. There are a few ways you can calculate the calories in these foods yourself.
Step 1
Select a method of finding the nutrition information. If you have a packaged food, the nutrition label is the way to go, but if not, select a book, website or database that has these values. The USDA nutrient database, which is freely available online, is one reliable source (see Resources). The database can be downloaded to your PC and used in Excel, or searched interactively online for thousands of fresh, packaged and restaurant foods. You can also go to specific food products' websites and often find the information if you have discarded the packaging or eaten at someone else's house.
Step 2
Bring together a list of all the foods you consumed in a given meal or day, along with the serving sizes you ate. If your meal involves a variety of foods in odd quantities, then you will have to do a little homework. As an example, suppose your meal had six ounces of beef tenderloin, one-half cup of broccoli with a quarter cup of melted cheddar on top, a large baked potato with one tablespoon of butter and a 4 oz. glass of wine.
Step 3
Look up the calories for each of these foods in its standard serving size from your chosen source of calorie information. For example, in the USDA database, you will find the following serving sizes with the attached calories: beef tenderloin, 3 oz. 269 calories; broccoli, one-half cup, 27 calories; cheddar cheese, 1 cup melted, 983 calories; white potato, one large with skin, 281 calories; whipped butter, 1 tbsp., 67 calories; and red table wine, 5 oz., 125 calories.
Step 4
Convert the calorie counts for these standard serving sizes into the amounts for your meal by multiplying the standard calories by a conversion factor. For example, the broccoli, potato and butter are already in the sizes you ate, so their calories do not change. The beef, however, was given in a 3 oz. serving, but the serving in this example was 6 oz., which is double the standard size. Simply multiply the calories for the beef tenderloin by two: 269 x 2 = 537 calories for your 6 oz. serving. The cheddar was given as a full cup, whereas you only had a quarter, so your count is 983 x 1/4 = 246. Finally, the wine serving was 5 oz., and you only consumed four, so take 4/5 of the 125 calories: 125 x 4/5 = 100 calories.
Step 5
Add up the calories for the meal from steps 3 and 4. The total for the example steak dinner is beef + broccoli + cheese + potato + butter + wine = 537 + 27 + 246 + 281 + 67 + 100 = 1,259 calories.
Tips and Warnings
- Even if all your different food selections have nutritional labels, it can still sometimes be easier to do the math with a calorie-counting database or website than a calculator. Many restaurants and fast food chains now publish the nutrition information for their menus on their websites or have them available for you to take home, so that can save you the measuring and weighing or guesswork you might do to figure out serving sizes.
- Some sizable discrepancies can exist between very similar-sounding food products. For example, in the USDA database, there are seven different products with "pasteurized processed American cheese" in the name, with calorie counts ranging from 14 to 34--more than double--for a single slice, so you need to carefully consider the weight and content of each product if you want to measure accurately.
Member Comments