Don't eat just before training. It's a rule I have followed since I started. Otherwise, just pace yourself. You might not be able to keep up at first, but that's alright. You will get there.
It's ok to eat just before training but just a light meal
I ate quite heavily just before training before and regretted it. Firstly, there is a possibility of vomitting. Secondly, eating heavily drains more energy because your body is using more energy to digest your food leaving you exhausted.
I have personally experienced all this before.