How are calories worked out?

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timeforwork
timeforwork Posts: 114 Member
in Health and Weight Loss
Just wondering how the amount of calories per piece of food is worked out? I don't mean this in a diet related way but more like a mad scientist in a lab experimenting type thing! Anyone know as Google tends to try to send you to calorie counting pages and I got fed up seeing debates about how many calories per egg ( must be a very common search!) thanks all in advance x

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  • jennifer_417
    jennifer_417 Posts: 12,344 Member
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    I don't know, but that is a very interesting question!
  • firfenwen
    firfenwen Posts: 1 Member
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    I'm pretty sure I read somewhere that the food is burned and the resulting heat and light energy is recorded as a measure of calories.
  • Amandajs232
    Amandajs232 Posts: 194 Member
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    firfenwen wrote: »
    I'm pretty sure I read somewhere that the food is burned and the resulting heat and light energy is recorded as a measure of calories.
    Yes that's how they do it. Kcal can vary quite a bit and even prepackaged products can be 10% out either way due to natural variances e.g. One portion of chicken or veg could have more water content than another. If you are trying to lose weight just log everything and it balances out. If a generic item try and find a realistic value i.e. A giant cake is not going to be 100kcals so don't choose this just because it is in the database, find the most realistic.

  • trigden1991
    trigden1991 Posts: 4,658 Member
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    timeforwork wrote: »
    Just wondering how the amount of calories per piece of food is worked out? I don't mean this in a diet related way but more like a mad scientist in a lab experimenting type thing! Anyone know as Google tends to try to send you to calorie counting pages and I got fed up seeing debates about how many calories per egg ( must be a very common search!) thanks all in advance x

    They use a bomb calorimeter which basically burns the food to allow them to calculate the energy output.
  • Xo_healthylc
    Xo_healthylc Posts: 77 Member
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    trigden1991 wrote: »
    timeforwork wrote: »
    Just wondering how the amount of calories per piece of food is worked out? I don't mean this in a diet related way but more like a mad scientist in a lab experimenting type thing! Anyone know as Google tends to try to send you to calorie counting pages and I got fed up seeing debates about how many calories per egg ( must be a very common search!) thanks all in advance x

    They use a bomb calorimeter which basically burns the food to allow them to calculate the energy output.

    What he said. We learned about it in biology in high school. It was always I weird to me that someone thought of it. Like hey lets burn some food and see if it can affect out weigh loss or gain. Lol.
  • daniip_la
    daniip_la Posts: 678 Member
    edited July 2016
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    I've taught general chemistry university students how to measure this in a low-tech setting.

    You burn a piece of food under a test tube full of water and measure the degrees of temperature change in the water, which correlates mathematically to the calories the piece of food contained.
  • timeforwork
    timeforwork Posts: 114 Member
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    Thanks all x nice to know a bit about the " c" word thats slowly becoming a part of my life! Xx

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