Is it okay to tell my friend that her gut bacteria isn't lazy, but she is?
Is your friend aware of your opinion?
She's aware of my opinion. And I'm not even sure that she is lazy, but she just needs someone to tell her that
You shouldn't say something so mean to your friend, especially if you have no real reason to. It's wrong to be so judgmental about how other people live their lives.
Nah, she will appreciate the honesty.
I think you are trying to make a bad joke in lieu of judging her sense of motivation. You should try a different approach to more lightly touch on the topic of her laziness and try to give her a reason to be more energetic in her work.