I just eat till I'm full. I workout a lot (de-stress, combats fibromyalgia and I can't stand to be idle) and stay so busy it doesn't really matter how much but the thoguht process shouldn't necessarily be how much you eat but more importantly what you eat.
Today is a new day. You will get out of it just what you put into it. If you have made mistakes, there is always another chance for you. And supposing you have tried and failed again and again, you may have a fresh start any moment you choose, for this thing we call 'Failure' is not the falling down, but the staying down.