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Matter being created from calorie intake? Interesting discussion

  1. Dec 17, 2006 #1
    Today my wife and I got into a little discussion on calorie intake and weight gain.

    A dietitian will tell you that if you take in an extra 3500 calories a day in your food, you will gain an extra 1lb if you do not burn off that 3500 calories. This is usually true, since there is no food out there that I am aware of that weighs less than 1lb and has the normal 2500 calories required a day plus the extra 3500 calories. 6,000 calories total.

    My wife was trying to explain to me that you can technically eat a small pill that contains 6,000 calories and gain 1lb after your body burns off the normal daily 2500 calories required by most humans. Even if the pill weighs only several grams.

    I was trying to explain that this is only true if you take in that 1lb through food or water which your body then turns into stored fat.

    She was also explaining an example of her friend's mother who had lupus and would gain 60lbs of water weight in a day and a half. I told her "She would have had to have taken in 60lbs of water for that to happen" and my wife insisted that she didn't, that the disease magically manifested 60lbs of matter from thin air.

    Now I know that matter cannot be created or destroyed under normal circumstances like metabolising food. Since she will not ever believe me, I was hoping someone out there with a strong physics background could shed some proof onto this subject.

    Unless humans have some special ability to absorb matter from the surrounding atmosphere around us then this would be impossible, right?
    Last edited: Dec 17, 2006
  2. jcsd
  3. Dec 17, 2006 #2


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    You're right and she's wrong, but if she asks, I'll deny I told your that. :eek:
  4. Dec 17, 2006 #3


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    I think she might be right but it's not as simple as it sounds. If you take just a 1g pill, your weight gain won't be more than 1g. If you take 1 pound of food and this 1g pill, the pill has more than enough energy so your body could just store the remaining 1 pound of food as fat. Or your metabolism could increase in order to use up all that energy (sugar high?). Or you could have diarrhea and the 1 pound of food just goes through like nothing.

    I would probably bet on a mixture of all 3. Too many calories causes weight gain; this is pretty much a fact. Eating a healthy amount of food will increase your metabolism; this is a general rule, it stops being true when you are 500 pounds and breathing leaves you breathless. Pretty much everything gives diarrhea so I just threw that in there.
  5. Dec 17, 2006 #4

    jim mcnamara

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    Conservation of matter. Matter is netiher created notr destroyed.

    You can drink 1 Kg of water and gain 1Kg of weight temporarily. Until it leaves in urine and expired water vapor. You can take a long walk on a hot day an lose weight - water again.

    When people speak of weight they generally are referring to tissue -muscle, bone, and primarily fat.

    To permanently gain one pound of fat you have to have consumed ~3500 Kcal of energy in the form of excess carbohydrate or fat, for example. The weight of food required to do that could vary. A lot.

    For butter at 718 kcal/100 grams, you would have to eat a 490g serving: 1.08 pounds. For cooked pasta, at 130 kcal/100 grams, you would have to eat 2.6 pounds of cooked pasta to gain enough calaories. And these are in excess of your daily 2000-2400 kcal.
    Last edited: Dec 17, 2006
  6. Dec 17, 2006 #5


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    If this pill was the only thing you ate, then this is impossible.

    Mass balance:

    [tex]mass~ gain,~ \Delta m = m_{in} - m_{out} [/tex]

    [tex]m_{in} = m_{food} + m_{air~inhaled} [/tex]

    [tex]m_{out} = m_{egested~and~excreted~waste} + m_{air~exhaled} [/tex]

    Typically, mas of air exhaled is a little greater than the mass inhaled. But to maximize the mass gain, let's hypothetically assume that the mass exhaled does not exceed the mass inhaled. Also, let's assume there's no egestion/excretion taking place during the time of this experiment.

    [tex]\Delta m(max) = m_{food} [/tex].
  7. Dec 17, 2006 #6


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    You cannot make a pill that has 6,000 Calories of energy, yet weighs only a few grams. The most energy-density macronutrient is fat, and fat has about 9 Calories per gram of energy. A portion of fat that has 6,000 Calories has a mass of about 700 grams. There is no food substance that has a higher energy density. Even if you could eat e.g. high explosives, your body would not have the matter (carbon) necessary to actually store that energy as fat.

    - Warren
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