Science Questions

Does internal gas affect your weight?

Sun, 17th Jan 2010

Listen Now    Download as mp3 from the show Does farting make you weigh less?

Question

Sandra asked:

What volume of gas does a person has to have to affect their own weight. Does having gas make you weigh more or less?

Answer

Diana -   Well we have had a bit of a discussion about this and I think what it comes down to is what your farts are composed of.  Of course, there is some hydrogen sulphide in there and occasionally some methane.  I think it depends what kind of bacteria you have in your gut but I think it was about five out of seven people will have methane produced in their farts.  And of course, methane is lighter than general gas (air) and therefore, younwould think if you have that in your gut, then it would make you a bit lighter.  But of course, thereís a question of pressure.  So, if you have a lot of gas in your body thatís under pressure, it would actually be denser than air and actually make you heavier.  What do you think Dave?

Dave -   Yeah.  The very things which could be in the gas, one which could really make the constituent is hydrogen which is one of the lightest gases we know of and that can be up to 50% of your flatulence and so if itís made mostly of hydrogen then itís going to be much less dense and the pressure change is going to be very, very small. So when you expel the gas, it could even make you heavier because the hydrogen couldíve been acting a bit like a helium balloon in floating you ever so slightly.

Diana -   I don't know if you could do a test by seeing if that gives a squeaky pop with a lighted splint?

Chris -   Maybe Kitchen Science for the future.

Multimedia

Subscribe Free

Related Content

Comments

Make a comment

Makes you weigh more. Mr. Scientist, Fri, 11th Dec 2009



Most people produce about 1 to 4 pints a day and pass gas about 14 times a day.

http://digestive.niddk.nih.gov/ddiseases/pubs/gas/ Chemistry4me, Sat, 12th Dec 2009

If you weigh yourself while standing in a swimming pool with the water half-way up your torso, you'll weigh less.

I actually conducted this experiment in our swimming pool when we lived in Mesa, AZ. Geezer, Sat, 12th Dec 2009


True, but they weigh less if you fill then with helium.

The composition of the gases in the gut is a bit variable but I bet that the overall mix is less dense than air. Any water vapour or methane would make the gas lighter. So would removing oxygen. The fly in the ointment would be CO2 and I don't know how much of that is present. Bored chemist, Sat, 12th Dec 2009


True, but they weigh less if you fill then with helium.

The composition of the gases in the gut is a bit variable but I bet that the overall mix is less dense than air. Any water vapour or methane would make the gas lighter. So would removing oxygen. The fly in the ointment would be CO2 and I don't know how much of that is present.


Don't forget that your bowel gases might not be at atmospheric pressure, so even if the mixture would have a density less than air, if the pressure is sufficient, it'll still make you heavier Nizzle, Wed, 16th Dec 2009

There's one to add to the top 10 experiments I never want to do; measure the gas pressure where the sun doesn't shine.
You may be right but I don't plan to cheack. Incidentally I forgot to add that hydrogen is part of the mix. If it were pure H2 then it would need to be under a lot of pressure to be denser than air. Bored chemist, Wed, 16th Dec 2009



If you think you are going to get extra points at your Weight Watchers meeting by farting before you get on the scales, I have some bad news for you....... Don_1, Thu, 17th Dec 2009



Maybe they have really accurate scales Nizzle, Thu, 17th Dec 2009

See the whole discussion | Make a comment

Wellcome Trust
EPSRC
Powered by UKfast
STFC
Genetics Society