New weight loss plan - Helium!

How much helium would an average human being have to ingest to weigh one pound less weight due to the added bouyancy?

http://en.wikipedia.org/wiki/Lifting_gas#Hydrogen_and_helium

Since a pound is 454 grams, you’d need about 400 liters of helium to lift one pound.

Of course, if you’re pumping yourself full of helium, that helium is under pressure, and so is more dense, and so has less lifting power. If the density of the pressurized helium is greater than the surrounding air, you get no lift at all.

There goes my plan to lose 5 pounds prior to summer.

Back when I was a kid, some bike stores would fill your bike tires with helium rather than compressed air to reduce weight.

It’s a stupid idea in the first place because the difference in weight is pretty damned small (although, even if compressed, helium’s density is still less than the density of ordinary air), but more because helium, being so small, leaks out much more easily than compressed air. Like the circus balloon you bought that is sitting on the floor the next day, you just lose too much air from the tires and have to pump them up again. Nice racket.

You’d just be farting helium? Are there any dangers of mixing helium and methane or would that just make your farts rise to nose height faster? Incressing the rapidity of smell would make the whole smelt it/dealt it debate even more confusing.

Almost forgot, Helium Farts - Band Name!

If you farted helium, would the flatulence come out sounding more highly pitched than normal?

I thought this was going to be a joke but I see it’s not. Nowadays auto tire shops charge extra for using nitrogen…

Helium can reduce your apparent weight only to the extent that it replaces something denser - presumably air.

You could gain a small advantage by breathing air in which the nitrogen had been replaced with helium (you still need the oxygen). Were talking a few liters here, so just a few grams of weight “lost”.

Beyond that, you have very little air inside you, so nothing to gain (lose?) from helium.

Could this be the single greatest question ever posed on the SDMBs?

According to Farscape, yes.

Quite - and if you replace the air in the biggest bodily space with pure helium, it causes loss of consciousness, possibly death.

GQ seems abnormally gassy today.

the nitrogen replacement isn’t the same as the helium-lightening racket. nitrogen doesn’t leak out through the rubber as easily as air, making for more stable tires. i guess to an extent this would be the same for helium and bike tires but… with the low speeds that kids are dealing with it’s really negligible.

//hijack/
Nitrogen is offered for filling car tyres because it is more stable than air, the pressure change at different temperatures is less than air, and I think it’s less likely to contain water vapour, which causes corrosion.

Sounds like a job for Mythbusters.

I think you could only possibly lose that much apparent weight if you took in enough helium to inflate your body like a balloon (i.e., increasing its buoyancy by raising its volume without much changing its actual mass). Thus any loss in apparent weight would be accompanied by an actual increase in apparent fatness (which is surely not the desired result).

All ideal gasses change pressure with temperature in exactly the same way, and nitrogen and oxygen are both excellent approximations to ideal gasses under Earthly conditions. As for leakage, the biggest factor is the mass of the molecules (since at a given temperature, lighter molecules are moving faster), and this would actually work against nitrogen.

Excellent question!

You know how sometimes you have those squeaky high-pitched farts? If you had those while on helium would they be so high-pitched that only dogs could here them? It would make it easier to blame the dog.

pchem>physics in this case. the nitrogen molecule is less massive, but volumetrically bigger.