They burn it in a closed container and measure how much heat is released. A (kilo)calorie is defined as the energy needed to heat a liter of water by 1°C
How does the energy released by burning compare to the energy your body can extract through digestion? No idea!
If you have a Lego tower and wonder “how many Lego bricks are in that tower?” you can smash the tower and count all the individual pieces. You can even count up how many blue pieces, how many red pieces, etc
For calories we don’t smash the food, but instead we set the food on fire and count up all the pieces of smoke. We can even count up how many different pieces like the red and blue Legos above! And we know that, hypothetically, each piece of blue smoke has 2 energies, each red piece has 4 energies, etc then we add it all up and know how much energy was on there
Some people figured out that we get energy from three different things called macronutrients in food: protein, carbohydrates, and fat. These build food like Legos build a tower.
We know how much energy (calories) is in an average gram of each macronutrient from burning those things up and seeing how much energy was released
Then we can just count up how much of each nutrient is in the food, multiply it by the values found earlier, and get a calorie total.
Macronutrients (Carbohydrates, Protein, Fat) all have a set amount of calories per quantity: Carbohydrates/Protein at 4 calories per gram and Fat at 9 calories per gram. Btw, while alcohol isn’t a macronutrient it has 7 calories per gram.
The ingredients have a specified amount of macronutrients, so all you have to do is add them and multiply by the calorie amount.
1 calorie is the amount of heat needed to warm up 1 mL of water by 1 degree C.
So they use a device called a “calorimeter” where you dry the food and then literally burn it in a little container sitting in water, and then carefully measure how much the water heats up. Since you know exactly how much water is in the tank and how much it warmed up from burning the food, the temperature change tells you how many calories there are.
Also note, 1 Calorie (same as 1 kcal or “food calories”) = 1000 calories
All these bomb calorimeter answers are correct, but there’s a caveat. Companies don’t necessarily do this for every food product. Instead, they often use standardized measures published (in the U.S. at least) by USDA for the calories and macronutrients in the raw ingredients. Once you know all that, you can calculate the amounts for the final product.
Researchers burn food in a special instrument that detects the amount of heat given off. But after that, they record how much each ingredient burns off, and food producers use that data to calculate the calorie information for their products. I don’t think individual producers usually do the scientific measurements that researchers do.
This is off topic, your use of the term people feels weird to me. Like you can’t be a person who gets trained and can do it yourself. Or like it’s a hidden secret only a few can do.
*This is if OP is american. Fighting the American Idiocracy.
They essentially burn the food and see how much energy it releases. A calorie is the amount of energy it takes to raise a gram of water 1 degree Celsius. So you burn the food and see how much it heats up water.
Fat is 9 calories per gram, and protein and carbs are 4 calories per gram. Alcohol is 7 calories per gram which people often leave out when discussing micronutrients calorie amounts.
Comments
Calories are a measure of energy. If you burn all the food, you can detect how much energy was put out in the form of heat.
They burn it in a closed container and measure how much heat is released. A (kilo)calorie is defined as the energy needed to heat a liter of water by 1°C
How does the energy released by burning compare to the energy your body can extract through digestion? No idea!
If you have a Lego tower and wonder “how many Lego bricks are in that tower?” you can smash the tower and count all the individual pieces. You can even count up how many blue pieces, how many red pieces, etc
For calories we don’t smash the food, but instead we set the food on fire and count up all the pieces of smoke. We can even count up how many different pieces like the red and blue Legos above! And we know that, hypothetically, each piece of blue smoke has 2 energies, each red piece has 4 energies, etc then we add it all up and know how much energy was on thereSome people figured out that we get energy from three different things called macronutrients in food: protein, carbohydrates, and fat. These build food like Legos build a tower.
We know how much energy (calories) is in an average gram of each macronutrient from burning those things up and seeing how much energy was released
Then we can just count up how much of each nutrient is in the food, multiply it by the values found earlier, and get a calorie total.
By their macronutrient count.
Macronutrients (Carbohydrates, Protein, Fat) all have a set amount of calories per quantity: Carbohydrates/Protein at 4 calories per gram and Fat at 9 calories per gram. Btw, while alcohol isn’t a macronutrient it has 7 calories per gram.
The ingredients have a specified amount of macronutrients, so all you have to do is add them and multiply by the calorie amount.
1 calorie is the amount of heat needed to warm up 1 mL of water by 1 degree C.
So they use a device called a “calorimeter” where you dry the food and then literally burn it in a little container sitting in water, and then carefully measure how much the water heats up. Since you know exactly how much water is in the tank and how much it warmed up from burning the food, the temperature change tells you how many calories there are.
Also note, 1 Calorie (same as 1 kcal or “food calories”) = 1000 calories
All these bomb calorimeter answers are correct, but there’s a caveat. Companies don’t necessarily do this for every food product. Instead, they often use standardized measures published (in the U.S. at least) by USDA for the calories and macronutrients in the raw ingredients. Once you know all that, you can calculate the amounts for the final product.
Researchers burn food in a special instrument that detects the amount of heat given off. But after that, they record how much each ingredient burns off, and food producers use that data to calculate the calorie information for their products. I don’t think individual producers usually do the scientific measurements that researchers do.
you literally blow it up with a bomb
bomb calorimeter
Bomb calorimeter. They put a steak in the chamber and … phwomp! … (/s)
This is off topic, your use of the term people feels weird to me. Like you can’t be a person who gets trained and can do it yourself. Or like it’s a hidden secret only a few can do.
*This is if OP is american. Fighting the American Idiocracy.
They essentially burn the food and see how much energy it releases. A calorie is the amount of energy it takes to raise a gram of water 1 degree Celsius. So you burn the food and see how much it heats up water.
Fat is 9 calories per gram, and protein and carbs are 4 calories per gram. Alcohol is 7 calories per gram which people often leave out when discussing micronutrients calorie amounts.