eating calories back

If you eat back all the calories you earned exercising you would be would losing at the same rate as if you didn't exercise and just ate the regular allotted calories. If you didn't eat them back you could lose more, so long as your not eating too little. The amount of calories it sets you up with to start is based on your weekly goal. Eat too much and don't burn them, you will loose less. Eat less, and burn more you will lose more.

Exercise lets you eat more, and increases muscle and metabolism, but you certainly can lose weight without exercising. It's all about the calorie deficit.