How do they calculate the calorie and fat content of foods?

Question

How do they calculate the calorie and fat content of foods?

Answer 1

"They" are food chemists.  They pulverize the food and through a serious of chemical extractions can separate the fat of the food.  Weigh the fat and volia... fat grams are found.  This is true for determining vitamin and mineral and other nutrient content as well.  Just different chemical extractions for each.  

As for calculating calorie well that is as simple as burning the food to determine heat energy released then doing a mathematical calculation to convert to calorie.

Answer 2

i think there is a computer program that you enter your ingredients into and it tells you your calorie and fat content etc. it might even print out a label.  i don't remember for sure.

Answer 3

It's true there are computer programs and it's also true that there are books published with nutritional composition of various foods or ingredients.  So you can look up ingredients and calculate the nutritional composition of a complex meal.  

But the question remains where do the computer programs and books get their information?  It all originally comes from laboratory analysis.  Believe it or not the caloric content is determined by a method called bomb calorimetry where a weighted amount of food is placed in a closed container and burned completely and the heat given off is measured.  You can calculate the caloric content from that.  

For fat the food is mixed with ether and the fat dissolves in the ether and then the ether is evaporated.  What's left is the fat.

It's a little more complicated than I have explained it ( so you scientists please don't jump on me) but that's the jest of it.  Good question.

PhD  Food Chemistry and Nutrition

Answer 4

They calculate calories by how much energy it would take to work the food off. The definition of a calorie is a unit used to measure energy, its the amount of energy needed to raise the temp of one kilogram of water to one degree celsius.