Calories counting question

[SamiG]

As i am trying to lose weight i am counting calories... I am staying under my calorie count and am also burning at least 500 calories at the gym and i go 4+ times a week. So say i eat 1400 calories in a whole day, and work off 500 calories that day also, this leaves me with a calorie count of 900. Is this a good thing? am i supposed to eat to make up for the 500 calories i worked off? because that just doesnt make sense... but i also know only having 900 calories in a day is not healthy....

So can someone please explain to me how calorie counting to LOSE weight is supposed to work?