Well I have no old ways since I am still doing the same bad habits,
however my advice to you would be to keep busy, and not let yourself have time to overeat - but just have the right amount of time to eat a healthy meal.
Keep your mind busy as well. I find that the less i sit around alone in my room - the less i think about my eating issues, and the less i eat as well. Even though you might feel like theres an empty hole inside of you in which your sisters presents can only fill, you have to remember that food is not what can fill that space.
Be strong and don't fall into the same traps as I have. Eating too much food or not enough food won't make other problems go away.