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Thread: Energy measurement system in foods, why calories?

  1. #1 Energy measurement system in foods, why calories? 
    Forum Ph.D. Raziell's Avatar
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    Why is calories such a good way to measure the energy of foods?

    Are there any other good options?

    How do they actually meassure it?

    It seems to be measuring energy only, and not quality - isnt this system therefore very flawed?

    Im puzzled that we just accept calories as is, why isnt there better ways to find out exactly how much specific foods benefit us in various ways?

    My beef with calories is that it seems to only value energy, cynical as i am it seems to only be valued as fuel for humans, humans being a tool for society. Calories doesent give any hints at healthiness of food at all.


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  3. #2  
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    Hi Raziell,

    A calorie represents the amount of energy required to increase the temperature of 1g of water by 1*C. Since mammals expend a lot of energy in maintaining the body -including the blood - at a certain temperature (i.e. thermoregulation), it is possible that our reliance on the calorie as a measure of the energy content in foods is due to a 'mammalian bias', if you will.

    As for the ineptness of the concept of a 'calorie' in providing information about the healthiness - or otherwise - of foods... the calorie content is useful insofar as it enables a person to gauge whether they are satisfying, exceeding or failing to meet their target energy intake. It is nigh impossible to devise a singular unit that would give a comprehensive description of the healthiness or otherwise of foods. This is because foods are typically made up of several different ingredients, each of which will have some beneicial and some adverse properties. Also, the healthiness or otherwise of a food depends on the amount of the food eaten and on the frequency with which those foods are eaten.

    Tri ~


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  4. #3  
    Forum Ph.D. Raziell's Avatar
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    Thanks for the answer
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  5. #4  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    We just use the Calorie because it is an older measure of energy than the joule, and it is historically used for food (and it used to be used for fuel) because the bomb calorimeter was used historically to make these kinds of measurements. It has stuck around because common people are slower to change units than scientist, given enough government effort we could all be using KJ.
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  6. #5 Re: Energy measurement system in foods, why calories? 
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    Quote Originally Posted by Raziell
    Why is calories such a good way to measure the energy of foods?

    Are there any other good options?

    How do they actually meassure it?

    It seems to be measuring energy only, and not quality - isnt this system therefore very flawed?

    Im puzzled that we just accept calories as is, why isnt there better ways to find out exactly how much specific foods benefit us in various ways?

    My beef with calories is that it seems to only value energy, cynical as i am it seems to only be valued as fuel for humans, humans being a tool for society. Calories doesent give any hints at healthiness of food at all.
    The energy in food is measured in calories. It is a measurement. It is a way of measuring how much energy different kinds of food provide or how much potential energy that food has.

    It's not like that the energy of food is calculated as it is. Each food item has energy out which there is a part called metabolizable energy intake (MEI). Normally this value is obtained by multiplying the total amount of energy associated with a food item by 85%, which is the typical amount of energy actually obtained by a human after respiration has been completed. Hence the amount of calories which is considered is normally this MEI and accordingly the food is taken.
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  7. #6  
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    The calorie content of our food is only one measure, but it's the one most people are concerned about because it will determine whether we gain or lose weight.

    Of course there are other nutritional elements to worry about, and we can find a lot of information on food package labels concerning carbohydrates, fat, protein, fiber, and various vitamins. If you want to keep track of it you can find computer programs or online diet journals where you can log your meals every day and count up all the nutrients consumed.
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  8. #7  
    Forum Radioactive Isotope skeptic's Avatar
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    As tired and sleepy said, it is only tradition that leads us to use calories. A more scientific measurement is the joule, and kilojoules are increasingly being used alongside, or to replace calories. These things take time.

    There are roughly 4.2 joules per calorie. A joule is the amount of energy required to move one metre against a force of one Newton. A Newton is the force required to accelerate one kilogram mass by one metre per second per second.
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