"Dad, when you fart, do you lose or gain weight?"

[Skammer]

@Inner_Stickler

So I guess, the question is, when we say lose weight, do we mean net or gross.

In the case of my farts, it is almost always gross.

[Toxgoddess]

@Leo_Bloom

So I googled “density of flatus”–I was going to ask here, but some times I get yelled at for not doing minimal research–and the top hit, would you believe it, was Typical Density of Flatulence. What kind of people would bother wondering about that?

“Gut” by Mary Roach. More than you ever wanted to know, including a comprehensive review of the flatulence research field.

I don’t believe the book addressed this question, though. Kudos to your 13-year-old. She has an admirable scientific mindset.

[cochrane]

Sounds like one for the Mythbusters!

[Shodan]

Sometimes I am tremendously proud to be a Doper; other times I am deeply ashamed. Often, like now, I can’t make up my mind.

I also can’t believe I get drawn into these discussions. Nonetheless -

I am going to assert that one loses weight upon cracking one off. My reasoning is as follows:

Flatus is mostly methane and hydrogen (sulphide, IIANM). Both lighter than air, as the Revered Master points out. I cannot believe the human intestine can hold methane under such pressure as to liquefy methane, or even come near. Organic chem was many moons ago for old Shodan - does anyone know how much pressure one has to store methane under before it becomes heavier than air? I have Googled, but without success.

And I feel morally obligated to republish this ode to the muscle that makes it all possible -

They say man has succeeded where the animal fails because of the clever use of his hands, yet when compared to the hands, the sphincter ani is far superior. If you place into your cupped hands a mixture of fluid, solid and gas and then through an opening at the bottom try to let only the gas escape, you will fail. Yet the anal sphincter can do it. The sphincter can apparently differentiate between solid, liquid and gas. It apparently can tell whether its owner is alone or with someone, whether standing or sitting down, whether its owner has his pants on or off. No other muscle of the body is such a protector of the dignity of man, yet so ready to come to his relief.

Regards,
Shodan