How do they work out how many calories are in food?

Question

How do they actually know that e.g. a packet of noodles contains 200 calories? What do they do to it to find out the amount?

Answer 1

They literally burn the food in a special device and measure the heat energy given off. The original heat energy used to burn the food sample is subtracted and the difference is the caloric content of the food.

Answer 2

Encyclopedia

Calorie

Definition: [KAL-uh-ree] A unit measuring the energy value of foods, calibrated by the quantity of heat required to raise the temperature of 1 gram of water by one degree celsius at a pressure of one atmosphere.

The four sources from which calories are obtained are alcohol, carbohydrates, fats and proteins, however all these sources are not equal. For example, fat packs a hefty 9 calories per gram, over twice as much as the 4 calories per gram carried by both carbohydrates and proteins. Alcohol has 7 calories per gram, almost as many as fat.

Clearly, fats and alcohol have a much higher caloric density than carbohydrates and proteins, so it's obvious that a 6-ounce serving of steak will be much more expensive calorically than 6 ounces of cauliflower.


--Copyright (c) 1995 by Barron's Educational Series, from The New Food Lover's Companion, Second Edition, by Sharon Tyler Herbst

Answer 3

Different food groups contain different amounts of calories.
1gramme of protein gives 4.2 calories
1 gramme of fat gives 9 calories
1 gramme of carbohydrates give 4.2 calories
Vegetables and fruit don't have much energy value and few calories.
So multiply the weight in grammes of the food by the number of calories the food type givesand you get the caloric value.
The packet of noodles probably contains 50g of carbohydrates,which equals 200calories(50 x 4.2)

Answer 4

Very simple. Fat is roughly 9 kcal/1 gramm, carbs around 4 kcal/1 gramm and 1 gramm of protein is also about 4 kcal. Look at the food you are having and find out how many gramms of protein, carb and fat there is: e.g. 10g of fat, 25g of protein and 100g of carbohydrate then 10g x 9kcal = 90kcal, 25g X 4kcal = 100kcal, 100g X 4kcal = 400 kcal, then 90kcal + 100kcal + 400kcal = 590 kcal, which is about the amount of a plate of dinner without starters or deserts.

Answer 5

Today it's very simple cause if you just input the name of the product you want the calories for like for example noodles calories the internet gives you thousands of answers.

Answer 6

Ok... this is a good question... How the hell does someone can be sure that glass of COKE have 200 calories... how can they count the calories?
Of course there is scientific explanation which I don´t care.... But come on.... this is ridiculous...

Answer 7

they use a machine caled a calorometer(hope i spelt tht right) these burn small amounts and measure the amount of energy given off. there are diffrent types of calorometer and are often used to determine how safe chemicals are in the chemical industry(in case of explosions). remember that the calorometer gives the total amouint of energy in the food and not the amount your body will extract(eg peanuts are loaded with calories but will pass undigested through you)

Answer 8

The extract mathematically and chemically the amount of molecules in noodles that have the potential to produce energy.

Answer 9

I think Savage Steve is right too. I remember our science teacher burning a peanut in a little burner thing and measuring how long it took to burn, and that decided how many calories it had.... but how would you burn coke?? I don't know!

Answer 10

They burn it and measure the amount of energy given off by the flame. I remember doing this experiment at school (early 1980's)