Okay, what to eat BEFORE a work out... and does it matter?

I asked a question about what to eat after a work out, and after some research as well, I now know what to eat after a work out… but I am still confused as to what to eat BEFORE it, and whether what I eat will matter or affect my work out. I’m not working out to lose weight, TOO much. I am 130 5’4”, so I’m not exactly overweight. But, I don’t want to gain weight, and I do want to get fit. I have lost 20 pounds by going on an empty stomach with plenty of water, but now it’s getting harder to control the hunger pains in the morning and I eat something, then I worry about whether this will affect the work out or not.

For example, I had some cereal and milk this morning. That’s probably some where around 300–400 calories and the cereal had 9 grams of fat, which shocked me… Now I’m feeling like I shouldn’t even bothering running and I should go tomorrow with a much less fattening meal, like yogurt or a banana. This happens often ):

I would love some specific answers, like what specific foods should I avoid and which should I take?