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

[iamthewalrus_3]

@bump

So you definitely lose mass, but your actual weight loss may vary, depending on the gaseous content of your flatus and its relative density compared with air.

Depends on your definition of weight. Weight is often defined strictly in terms of mass and gravitational force, making it irrelevant what atmosphere you’re standing in.

If you define weight as the reading on a scale, then it matters.