You adjust your diet to your exercise, not the other way around. Here's how Sparkpeople determines its calculations: www.sparkpeople.com/resource/calorie_calcu
You set a reasonable weight loss goal, enter the amount of exercise you will do, and then Sparkpeople adjusts your program to account for this. The more you exercise, the more you will need to eat to support it.
What's y our current weight, target weight, and current weekly weight loss goal?