My friend Leigh Peele made this short video concerning common mistakes concerning counting calories and measuring your food.
And if you are someone that is trying to lose weight I can't overestimate the importance of knowing (not guessing) how much you are eating every day. Nobody wants to try and lose weight forever so you might as well go after it and get the results you want. After that it's all gravy (so to speak).
It's true you can't out train bad nutrition