How exactly do calorie deficits work?

I see some people say that if you need 1500 calories a day to lose weight, and you burn 200 exercising, that you need 200 more to make up for it.

However....
I see some people post that if you need 1500 calories a day and exercise, you don't need to make up for those lost calories, as long as you go them in. 

So, what is the real deal?

It depends on how much you burn to maintain and what your deficit it. So for example if you can maintain on 1800 and only eat 1500 to lose then your deficit is 300. If you exercise and burn an additional 200 then it will be 500. The recommended deficit to loose at a safe rate is around 600-1000. So you don't really need to eat an additional 200. Now if you are already at 1k before exercise then your deficit will be 1.2k. In that case you should eat more.

UD

Okay, but I'm 16 and my mini. is 1500.  To maintain, the calculator said 1800.  So what if I burn an extra 200 (while eating 1500), do I need to eat 200? Because then that will take me to 1300 calories, and my mini. is 1500?

Okay, but I'm 16 and my mini. is 1500.  To maintain, the calculator said 1800.  So what if I burn an extra 200 (while eating 1500), do I need to eat 200? Because then that will take me to 1300 calories, and my mini. is 1500?

No, you don't need to eat the extra 200 calories.  You'll be eating enough food to get the nutrition you need (assuming you're making good choices) and your deficit would be 500 calories/day - which is a good level for steady weight loss.  That said, at 16, are you completely and totally sedentary?  No walking to school, the mall, etc.?  No gym class?  No part time job involving standing?  Very few teens are totally sedentary, so you may well be underestimating your burn.

Thanks..that really cleared things up.  No I'm not totally sedentary.  I walk for about 45 minutes around where I live, and walk here and there.  I also do a lot of house cleaning.  Schools out now, so no sports.