im sure you know what eating wrong is
so how little can you train to maintain your optimum shape and condition?
I can only assume eating "wrong" is either eating too much or eating too little or not meeting your nutritional needs. You would have to go out of your way to do any of those things.
Maintaining shape and condition on minimum amount of training would be a good experiment. I think its safe to say someone could do so with 1-3 days of training. They may even be able to maintain without any weights with other forms of training. Its a good question worth pursuing for some people.
Not for me though, I love to lift weights as I get great satisfaction and enjoyment from it and the health benefits are undeniable. Even if I never got any gains whatsoever, I would still lift weights. I really like doing it.