# How much energy does the average human body have at a given time?

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If you could just take all the energy from an average human being, would you be able to power a 40 watt lightbulb with it? If so, for how long?

Can anybody give me a good idea of the comparable amount of energy in a human being?

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If you could just take all the energy from an average human being, would you be able to power a 40 watt lightbulb with it?

If you extracted it at 40 watts, then yes.(or at least fed the enery through at 40 watts).

how long depends on the size of the person. i have no idea how much energy(assuming chemical energy) is in the human body. but the time in seconds would be (Energy retrieved in joules)/40

i'd say the 40 watt bulb would stay lit for a long time since the body idles at around 100 watts.

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Joules is capacity right? Anybody know how many joules the average human body has at a given time?

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Joules is a measure of the amount of energy, not really a capacity.

the only way to really work this out with any accuracy(short of burning a body to determine the energy released by calorimetry) is to take the energy of all the mass and go from there.

lets say we have an 80kg human. the maximum energy that can be released is if there was a total mass conversion.

E=mc^2 (we'll assume momentum is zero)

E= 80*9*10^16

=7200000000000000000 J

=7.2 EJ(exa-joules)

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i dont know if it helps, but a healthy human can maintain around 150-250 watts for almost an hour, top athletes can hold it at 300 watts but are completely exhusted after an hour. (stats from tour de france)

also, i've found that the type of breakfast you have is very important if you intend to maintian any wattage for a respectable time,

1 watt second=1joule

check the back of cerial packets for rough estimates, look at the energy per serving.

at any given time, my estimates about avaliable energy someone has would be in tens of MJ

a small bottle of apple juice has over 200KJ, sugar is potent stuff.

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Ahh thats given me an idea for an example. david blane survived without food for 40 days(?).

40*24*3600=3456000 seconds

3456000*100=345600000 joules

=345 MJ

now, this isn't the total chemical energy that he had seeing as he still wasn't dead and you could extract more energy by burning him(who else would want to see that?). but its a rough estimate.

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The label on my cooking oil tells me that it's 91.4 g of fat per 100 ml and it's 3382KJ/ 100 ml. Since it's practically pure fat that gives 37KJ per gram. Near enough to 1000 seconds of power for a 40 Watt lamp for each gram of fat.

If all Mr Blane lost was fat he would have lost about 10KG in weight.

Proteins store roughly half the energy on a weight for weight basis.

(My personal opinion is that he also lost credibillity, but I don't think that has an energy value).

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so would it actually be possible do light a light globe attached to the body? lol

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When you talk about long-term fasting, there is a trick reason why you can't just drink water and quiet down to alpha state. Cells continue to die and need to be replaced! We are a successful rate process, as long as we are.