So I was having a heated discussion today over beers with a few friends, and…
We’re trying to decide whether someone loses weight or gains weight when they fart.
Assuming a typical after-beer fart, I would have to say lose weight. I say this because it seems my body doesn’t change shape at all when I fart, so my total volume hasn’t changed, but my density has gone down, hence a loss of weight.
Now, on the other hand, my friends were trying to convince me that depending on the particular makeup of the fart, you could conceivably gain weight. Apparently they believe that the as yet to be farted gas creates a buoyant force on your body, actually lowering your total weight. Hence when you let that one rip, you’d lose the buoyant force and then gain weight.
Now their description seems to work, but only if you’ve got a massive fart all bottled up and it’s not under much pressure. I don’t believe that’s the general case.
So anyone care to enlighten us? Any scientific experiments been done? I’d prefer to avoid having to do too much drinking and trying to weight ourselves before and after letting one rip…
Farts, though pleasing to the ear, smell. If it smells there has to be something corporal there, even if it’s only a gas, to smell. Even gases have mass. You’re losing weight.
Your density, depending on the awesomeness of your abs and such like that, might possibly go up or down.
If you had two identical plastic bags, filled one with air and put them on a scale, which way would it tip? The one with air has more mass, but it also has more buoyancy. The amount of buoyant force is equal to the weight of the air displaced by the bag, which is the same as the weight of the air inside the bag. So the scale will not tip either way.
Now what if one bag was empty, and one was filled with helium? The buoyant force is the same as if it were filled by air, but now the weight of the gas inside is less. So a helium-filled bag will be lighter.
It should be the same with fart - it depends on the composition. If it was the same density as air, then when you release the fart you lose some weight and lose the exact same amount of buyoant force, and you will weigh the same. If your fart is lighter, then releasing the fart will make you weigh more.
So is fart lighter than air? I’m not too sure - methane and water vapor are both lighter than air, but CO2 is heavier, and fart contains all these. I’d guess it’s pretty close to the density of air, possibly a bit lighter.
Well it may not be very scientific, but in the movie Willy Wonka and the Chocolate Factory (or something like that) has a scene where a dad and his son drink some kind of very fizzy soda, which causes gas bad enough to lift them off the ground. They finally get down by belching and thereby releasing the gas. I suppose they could also have farted.
So in light of this new evidence, I contend that you weigh more after farting.
Pure methane, at an equal density, will weight a little more than half as much as an equal volume of air. However, methane gas in your stomach is under pressure, enough so that I can confidently state it offers you no buoyancy at all. It couldn’t offer you much more than a few grams of buoyancy, even if you had gas sacs regulated to outside air pressure. You’re going to eject fractions of a gram of methane in a fart, grams at most, and it’s not going to change your weight appreciably either way. At most, you’d lose a very little bit.