Do I lose weight when I expel gas?

Don’t think it would matter.

That type of diet, you might loose all your friends. :-)

depends on how full of shit you are.

Technically losing weight, yes. But it’s generally weight that you “gained” by eating food—it’s not removing any “permanent” body weight.

You lose friends ;)

You gain weight (where weight is defined as vertical force exerted by a mass as a result of gravity) after a fart.

Methane is lighter than air. When you fart, you release methane and hence lose buoyancy. The result is that, on a scale, you would appear to get heavier.

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Burping, on the other hand, typically involves the ingestion of air. A burp of that nature won’t have any effect.

But if you drink a lot of carbonated soda, then your burp may be primarily comprise of CO2. Carbon dioxide is heavier than air. In that case, you’d actually lose weight.

Actually, ⅔ of adults have no methane in their farts. Methane is a product of intestinal bacteria, but for unknown reasons methane in farts appears to run in families. The main constituent of flatus gas is nitrogen, which is only a tiny bit denser than atmospheric air.
Even if you are a methane farter, chances are the methane content is only around 10% tops.

HAH! Then my roomate should’ve lost 30 lbs. since yesterday when i got back to school :/... I don’t think that happened, unfortunatly… But i might lose weight by losing my apetite because of her stank haha

You also weigh less when you exhale while standing on the scales.

@robmandu but the gain of weight caused by expelling the lighter than air is cancelled by the rocket effect of the expulsion.

@Harp by golly you are right.
On average, a fart is composed of about 59 percent nitrogen, 21 percent hydrogen, 9 percent carbon dioxide, 7 percent methane and 4 percent oxygen. Less than 1 percent of their makeup is what makes farts stink.
gleaned from
http://bodyodd.msnbc.msn.com/archive/2008/03/19/786305.aspx

@Harp, so it’s not the methane that produces the green flame? It must be the nitrogen?

@gailcalled- That’s because you are losing carbon along with the atmosphere you are taking in. I was really wondering about methane and bouyancy. Of course you are losing mass. I probably shouldn’t have used “weight” in my question. I think @robmandu gave me a pretty great answer.

Since flactulants are usually hot air, they are lighter than the air around you and go upward. When you pass gas you lose this buoyancy and you actually weigh more. Sorry.

@Yetanotheruser Nitrogen is inert, so it won’t burn. The flammability comes from methane (if it’s present) and from hydrogen, which comes from breakdown of carbohydrates by intestinal bacteria. Depending on how many carbs are in the diet and the population of intestinal microbes, hydrogen content can be up to 50% of flatus gas, which would indeed make for a very light mixture. But hydrogen can also be as low as 5%.

So I’m afraid @AstroChuck will have to undergo a fart analysis to accurately determine whether he can fart his weight away.

Why does it make a green flame when ignited?

@Harp- I don’t envy the person administrating that analysis. :)

if so, there would be a lot of Fluther members that would be anorexic!

@Yetanotheruser Methane burns blue, and hydrogen has a colorless flame. If there’s a green flame (I’ll have to take your word for that), then it would have to come from traces of other substances in the gas, rather than the gases themselves.

I’ve seen it! Really, I have! but it was a long time ago, and I don’t remember how much, if any, my consciousness was altered at the time!

Last time I saw that, the backflash caused first-degree burns on very sensitive areas, as well as some depilatory action. (Actually, I am guessing about the depilation based on the smell of singed hair; I didn’t actually inspect the guy!)

I have also seen people lose a couple of pounds after a fart, but doing so requires a change of pants.

Yes, but you need to exhale first and then hold your breath.