To calculate the grams of carbohydrate in the foods you eat using carbohydrate factors, you need a scale that gives weights in grams (not pounds and ounces) and a source of carbohydrate factors (either a list, package labels, or the USDA Nutrient Database, www.nal.usda.gov/fnic/foodcomp/search). It also helps to have a calculator. Here’s what to do:
- Place your plate (or bowl or cup) on your scale and set the scale to zero.
- Put the portion of food you plan to eat on the plate. Make sure the food is in the form you plan to eat it. For example, rice should be cooked before weighing, oranges should be peeled, and grapes should be removed from the stem.
- Note the total weight of the food in grams. Keep in mind that the total weight of the food is not the number of grams of carbohydrate in it.
- Find the food’s carbohydrate factor using your list, the Nutrition Facts panel of a package label, or the USDA Nutrient Database.
- Multiply the food’s total weight in grams by its carbohydrate factor. The result is the number of grams of carbohydrate in your portion of food.
You are having white rice as part of your meal. You put your plate on the scale, set it to zero, and dish up a portion of the cooked rice. Your scale tells you it weighs 250 grams.
From this Carbohydrate Factor Reference List, you find that the carbohydrate factor for white rice is 0.24 (meaning that 24% of the total weight of cooked rice is carbohydrate).
You multiply 250 grams by 0.24 to find the amount of carbohydrate you will be eating: 250 grams of cooked rice x 0.24 = 60 grams of carbohydrate.