How do we know that a particular food has how much calories and protiens and vitamins. What is the way to find

Question

I want to know how companies tell that their product has particular calories and proteins and vitamins. What is a scientific way to know whether they are telling the truth or not ?

Answer 1

There are a variety of methods they use to analyze the product, including burning it and measuring the amount of energy. Spectral analysis and chromatography are other methods that are used.

The Food & Drug Administration maintains a food database that tells you the makeup of the raw ingrediants. So, if your product contains 200 grams of flour, 10 grams of sugar, 50 grams of raisins, etc, you just add all the ingrediants together from the database and divide by the number of servings. You can download a copy of the database for yourself at this link:
http://www.ars.usda.gov/ba/bhnrc/ndl

Answer 2

If YOU want to know the actual calorie counts and whatnot for food, based on weight and size, then use websites such as www.calorieking.com. It is true that some companies try to fool their consumers with their nutritional info, and the FDA is even guilty of this. So go to one of these websites to find the truth, opposed to what the companies put on their packaging.