If your plan of attack is to count calories, you need to know two things: 1) how many calories you’re taking in a day and 2) how many you’re burning!
This calculator will tell you how many calories you burn without exercise (exercise will only make this number grow!). It may not be a very high number, but it will give you an idea of what your body is doing with the things you eat.
Click this link: http://www.fitness.com/tools/bmr/ then switch the measurements over to Imperial (pounds & inches) unless, of course, you just know how much you weigh in kilograms. Enter your height, weight, age, and gender… and now you know. 🙂