I could be wrong but the 1200 is the amount for healthy weight loss. So if you burn more you get to eat more, but that shouldn't lower the base 1200 number because then you would either be 1. In an unhealthy weight loss range or 2. Your body will go into starvation mode because your calorie intake is too low. Also keep in mind that the calories you want to have before and after a workout are to maximize the benefits of the workout. So you want to have your body loaded on protein to build muscles after a workout and you want to have carbs to be able to fully work during your exercise program. So I guess in short, you need calories and if you are working out you need more calories for your body to function like a well oiled machine.