How The Calorie Content Of Food Is Determined

October 18, 2019 0 By Ewald Bahringer


First, let’s make sure everybody here understands
what a calorie is. A calorie is just a measurement of energy- the amount of energy needed to
raise 1 gram of water 1 degree Celsius at standard atmospheric pressure. This makes
sense when talking about calories in food. Food provides energy and our bodies need this
energy to function throughout the day. I’m hoping to burn about 100 calories while writing
this response. If not, this 100 calorie snack pack won’t be as health conscious as I thought
and will go straight to my hips! Second, it’s also important to note that
Calories in food are actually measured in kilocalories, so 1000 actual calories for
every 1 Calorie listed. Manufacturers used to measure calories using
a “bomb calorimeter”. This process involved placing the food source in a sealed container
filled with water. They would then burn the food with electrical energy. After the food
had completely burned up, they would measure the water temperature to see how many degrees
it was raised and thus how many calories used. In 1990, under The Nutrition Labeling and
Education Act of 1990, the FDA began requiring food manufacturers to label the amounts of
nutrients and calories contained in their products. This act resulted in moving away
from the bomb calorimeter method for determining the number of calories in food. One reason
for this was to make it easier and less expensive for manufacturers to meet the standard. Another
was that the bomb calorimeter method measures all available calories in the product. Since
most foods contain indigestible components, like fiber, that pass through our system and
get excreted in the form of bum brownies, this would lead to a consistent overestimation
of ingested calories using the bomb calorimeter. Instead, they used an easier method known
as the Atwater system. This approach adds up the calories available
through the energy containing nutrients in the food item, like protein, carbohydrates,
fats, and alcohols. They use standard reference tables for common ingredients based on their
energy densities. Things like 4 kilocalories for proteins, 4 for carbohydrates, 3 for organic
acids, 9 for fats, and 7 for drinkable alcohols (ethanol). No wonder all that beer gives me
this soft belly! It has over 1.5 the calories per mass as proteins and carbohydrates (well
worth it though). So for a specific example, let’s say that
tasty snack you have before you jump on the treadmill contains 5g of protein, 10g of carbohydrates,
and 15g of fat. The label on the package would then read 225 Calories (or 225,000 calories
for those who can’t stand over simplification which results
in misconceptions!)