"If you are trying to lose weight, you'll need to cut your calorie intake. You need a deficit of about 3,500 calories a week to lose a pound per week." That's 500 calories per day that you need to cut out. "At the same time as you are cutting calorie intak, you should be increasing your level of physical activity- the number of calories you burn. In fact, the more physically active you can be, the better. If you can burn more calories through exercise, you wont have to cut your calorie intake as much."
I think that you can go to self.com to determine your personal calorie needs.
Calculate it yourself:
Multiply your weight by a factor of 13 to 16: 13 if you're sedentary, 14 if your daily activities keep you on your feet or you work out a couple times a week, 15 if you're a gym regular, 16 if you're extremely active. The product is the number of calories you need daily to maintain your weight.
To lose a pound a week, SELF magazine recommends that you eat 250 fewer calories per day (but don't go below 1200) and add 250 calories of exercise daily.