Just one. Please name just one. No, it's not carbon dioxide.
Last time I heard similar bullshit, the guy, when pressed, named "amino acids". Which is not a waste product, it's raw material. If you can't name even one, either you're making stuff up or you've been lied to.
Last time I heard tell of similar things, it was probably mild starvation-induced ketoacidosis.
Of course, it makes as much sense to say we shouldn't exercise because it releases "toxins"that make our muscles hurt. But, I'm guessing that's what people are normally misunderstanding in these cases.
Last time I heard similar bullshit, the guy, when pressed, named "amino acids". Which is not a waste product, it's raw material. If you can't name even one, either you're making stuff up or you've been lied to.