If you want to get the most from your workout, eat a tiny bit of carbohydrates before you workout. That will give you more energy so you can burn more calories. Then load up on lean protein afterward. Protein helps your body build muscle, which will improve your metabolism. Also, it is best if you can workout in the morning. But working out at night is certainly better than nothing at all.
I heard this on a TV show but am not sure which one. I'm changing what I eat before and after a workout as a result.