How do food manufacturers calculate the calorie count of packaged foods?

Answer 1

In order to answer this question, it helps to define a calorie. A calorie is a unit that is used to measure energy. The Calorie you see on a food package is actually a kilocalorie, or 1,000 calories. A Calorie (kcal) is the amount of energy needed to raise the temperature of 1 kilogram of water 1 degree Celsius. Sometimes the energy content of food is expressed in kilojoules (kj), a metric unit. One kcal equals 4.184 kj. So the Calorie on a food package is 1,000 times larger than the calorie used in chemistry and physics.

The original method used to determine the number of kcals in a given food directly measured the energy it produced.The food was placed in a sealed container surrounded by water--an apparatus known as a bomb calorimeter. The food was completely burned and the resulting rise in water temperature was measured. This method is not frequently used today.
The Nutrition Labeling and Education Act of 1990 (NLEA) currently dictates what information is presented on food labels. The NLEA requires that the Calorie level placed on a packaged food be calculated from food components. According to the National Data Lab (NDL), most of the calorie values in the USDA and industry food tables are based on an indirect calorie estimation made using the so-called Atwater system. In this system, calories are not determined directly by burning the foods. Instead, the total caloric value is calculated by adding up the calories provided by the energy-containing nutrients: protein, carbohydrate, fat and alcohol. Because carbohydrates contain some fiber that is not digested and utilized by the body, the fiber component is usually subtracted from the total carbohydrate before calculating the calories.


The Atwater system uses the average values of 4 Kcal/g for protein, 4 Kcal/g for carbohydrate, and 9 Kcal/g for fat. Alcohol is calculated at 7 Kcal/g. (These numbers were originally determined by burning and then averaging.) Thus the label on an energy bar that contains 10 g of protein, 20 g of carbohydrate and 9 g of fat would read 201 kcals or Calories. A complete discussion of this subject and the calories contained in more than 6,000 foods may be found on the National Data Lab web site at http://www.nal.usda.gov/fnic/foodcomp/. At this site you can also download the food database to a handheld computer. Another online tool that allows the user to total the calorie content of several foods is the Nutrition Analysis Tool at http://www.nat.uiuc.edu.

Answer 2

Food manufacturers have full control.
size, shape, color, texture, taste, calories, vitamins, fats

All the same, this becomes a manufactured product, and not natural. It hardly counts toward a quality diet.

I recommend that you read the South Beach Diet book, and learn the starting facts about good nutrition.

Answer 3

They take a set mass of the food and burn it in a sealed container called a bomb calorimeter and work out the temperature change. This change is proportional to the amount of calories that the food has

Answer 4

They know how much of each chemical is in the thing, then add the calories for each bit up.
They used to find calories by burning a substance and finding out ho much heat it gave off and for how long

Answer 5

Chemical analysis as well as an analysis of the recipe determines levels of fats, proteins, carbohydrates, etc. where standard caloric values are known. Using calorimetry to determine the caloric value overestimates the value, as fiber can burn but will not be digested by the body.

Answer 6

i don't know about that, but if you take the temp of 100mL of water in a aluminum can and then burn the food under it, then take the new temp of the water and then mult the difference in temp by 1000, that's how many calories are in the food item.

Answer 7

Calorific value of food is calculated by the formula

calorific value = (Fat x9 ) +(protein+carbohydrate)x4

carbohydrate is calculated from the formula
carbohydrate = 100 - ( protein+fat+ash+moisture)

There are international test methods for testing fat, protein, ash and moisture.

Answer 8

they burn the food and compare the heat to weight to time ratio and equate the Calories from that equation.

Answer 9

i think they burn it in a hot oven and they count how much energy is released with special equipment.

Answer 10

Yes I agree with what has been said