How Many Calories A Day ( Advice Needed )

To lose 12 lbs. set your goal to .5 lb. per week (a 250-calorie deficit), and be patient. Eating a 1,000-calorie deficit will not get you to your goal 4x faster. The less you have to lose, the more slowly it comes off. That's just the way the human body works.

Please, read the Sexypants post: http://www.myfitnesspal.com/topics/show/1080242-a-guide-to-get-you-started-on-your-path-to-sexypants

Is it safe? Depends what you mean by safe. It won't kill you to eat 1000 calories. Your body won't shut down fat loss, or anything crazy like that. What will happen is you may find yourself feeling awful, wanting to binge eat, having low to very low energy, poor sleep, etc. Part of why very low calories don't work is that they don't create as big of a deficit as you think they would. If you maintain on 1800 and cut to 1000 you might find that you are far less active for the day due to low energy levels. This is in turn means your TDEE is lower. I'd much rather prefer to eat a little more, and burn more calories by being active, then restrict my calories to such a low level. Remember that eating 1000 calories and burning 1500 is the same net difference as eating 1500 calories and burning 2000. Accept the person eating 1500 is less likely to miss out on vital nutrients because they have more calories to work with at the end of the day.