Yes, this is true - and if you think about it, can't be any different way, really. I mean, where else would it go? No chemical reaction can destroy any noticeab

Yes, this is true - and if you think about it, can't be any different way, really. I mean, where else would it go? No chemical reaction can destroy any noticeable amount of mass. Excretions - like peeing and pooping - don't carry out too much mass too. So how else you'd get rid of some mass?