Calorie question!

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psmd
psmd Posts: 764 Member
in Food and Nutrition
Just wondering, this may seem like a stupid question but how are calories in food determined? Like who comes up (and how) with the exact number of calories that an apple, or milk, or whatever, are?

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  • Aemely
    Aemely Posts: 694 Member
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    It's not a stupid question. :smiley:

    http://www.scientificamerican.com/article/how-do-food-manufacturers/

    "The Nutrition Labeling and Education Act of 1990 (NLEA) currently dictates what information is presented on food labels. The NLEA requires that the Calorie level placed on a packaged food be calculated from food components. According to the National Data Lab (NDL), most of the calorie values in the USDA and industry food tables are based on an indirect calorie estimation made using the so-called Atwater system. In this system, calories are not determined directly by burning the foods. Instead, the total caloric value is calculated by adding up the calories provided by the energy-containing nutrients: protein, carbohydrate, fat and alcohol. Because carbohydrates contain some fiber that is not digested and utilized by the body, the fiber component is usually subtracted from the total carbohydrate before calculating the calories."
  • Aemely
    Aemely Posts: 694 Member
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    See also: We Used To Actually Set Food on Fire to Figure Out How Many Calories It Had.

    :p:devil:
  • matt6050
    matt6050 Posts: 56 Member
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    Calories are derived using a combustion method called calorimetry. A substance (in this case, the food) is combusted in a vacuum chamber surrounded by water. The combustion raises the water temperature and the calorie (unit of heat) is determined.

    At least that's what I remember from chem...
  • blossomingbutterfly
    blossomingbutterfly Posts: 743 Member
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    I've wondered this on occasion too, thank you for asking! ;)
  • psmd
    psmd Posts: 764 Member
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    Huh, very scientific! I knew someone here would know, thanks!!!

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