I’m not trying to lose weight.....

I’m not trying to lose weight. I like my size now I just want to tone up. Pretty much doesn’t matter what I eat I stay the same size. But do I need to change what I eat in order to tone up? Is there anything I should include or exclude from my diet ? So far I’ve been walking to and around the park. Then I do some strengthening workouts and walk back home. And I’ve taken snacks & fast food out my “diet” but nothing else.