exercise calories

I would just make sure to eat at least 1200 calories everyday. Don't go under that and you should be fine.

I disagree with liltommysmommy. That 1200 is a generic number put out as an average of ALL women, and should not be regarded as a hard floor for all women.

In truth, the amount of deficit depends mostly on how much you have to lose. There are many other factors that go into it as well, such as fat distribution, fat age, genetic disposition to fat burning, resting metabolic rate, calorie ratio, times and amount of calories consumed (I.E. when you eat, and how much you eat at any one meal), exercise amount, exercise type, age, sex, VO2 Max, respiratory efficiency...etc.

While most of these are difficult to gauge, many can be averaged because the differences from the mean represent small amounts, but for some of these, the differences are rather large and mean that you can't just rely on 1200 being the right floor for you.

1 thing you need to check is how much you really need to lose to be in the healthy range, the less weight (fat) you need to lose, the smaller your deficit should be. Yes, I realize a smaller deficit means a longer time to lose the weight, but that's just a fact of life.

So to the OP, my answer is, no you can't really bank calories. The body doesn't work that way (not really), fat stored isn't burned the same way as food consumed, and thus you can't think of food not eaten as extra calories you can eat all at once.

But on the other hand, IMHO your diet should never be so strict that you can't bend it a bit for a special occasion. As long as special occasions are special and kept at a reasonable amount (say once a month or so) and you don't go overboard for each one (I.E. eating 400 or 500 extra calories 1 day a month will do very little or no damage in the long term, no need to adjust the rest of your schedule, in fact, adjusting will only cause you more problems in the long run!)