Do you gain weight when you expel gas?

Question

Methane gas, like helium, weighs less than air. When you let helium out of a balloon, it weighs more. Therefore, it seems reasonable that when a person "relieves" himself of excess gas (which is primarily lighter-than-air gases), he weighs more - if even only a small fraction of a pound.

I am not asking about "mass", only "weight" (on Earth).

Answer 1

Distinction needs to be made between "weight" and "mass" Of course, when the human body discards any matter at all, be it feces, spit, breath, or flatulence, it loses mass, because all of those things have mass. Weight, on the other hand, does depend on bouyancy in the atmosphere, and it's quite possible for the human body to lose or gain "weight" without any mass transfer at all. Many fish species take advantage of this, changing the volume of their bodies in order to either rise or sink in the ocean water. We probably can produce "volume in our bodies" through production of intestinal gases, thereby "becoming lighter and more like balloons", which means flatulence will reverse the effect, and thus we'll become heavier, as your question proposes. For this reason, I'm giving your brilliant question a star.

Answer 2

No, the ballon is NOT heavier when it is empty, it is more dense than the surrounding air when the helium is released. The helium inside the closed balloon makes it less dense than the surrounding air, thus it floats/rises until an equilibrium is reached. ALL MATTER HAS WEIGHT. Adding any amount of matter also adds weight.

*edit* ~ yes, yes, pardon the mass/weight confusion.

Answer 3

Wow... I bet you're right! This is kind of gross but I know that when a dead body is dumped in a body of water it will initially sink to below the water line. Then as the body begins to decompose, solids within the blood begin to turn to gas and this causes the body to float, it is at this stage that most bodies are found. If it is not found at this stage, the gasses will eventually escape the body and the body will sink to the bottom and may never be discovered. So... given this information, I would say your theory is probably correct!