[TheAmega]

The average Human body consumes approx. 2000 calories a day, this is your baseline. So, regardless of what you are doing (diet or exercise) your body consumes 2000 calories.
This creates and equation Calories In = Calories Out
Your calories out starts at 2000 and your calories in starts at 0 (for the beginning of the day).

Everything you eat increases calories in, every bit of exercise you do increases calories out. At the end of the day if Calories in > Calories out you gain wait. If Calories in = Calories out you maintain your weight and if Calories in < Calories out you lose weight.

To lose 1 lb you need to have a deficit of 3500 calories. Obviously you're not going to do it in one day (in fact it's even hard to achieve this in 1 week).

So yes, exercise. Try to start out slowly and build your way up. Even start with walking. I recomend finding a Yoga class, as it will ballance out all of the stress (muscle and joint tension) caused by running. Also look into minor weight training. Use household objects (text books are good), and go on the internet and look for good exercises for different parts of your body.

And cut out junk food. 1 snack size bag of chips can have over 600 calories. A Big Mac has 704. In fact avoid fast food like the plague (the average meal at the golden armpits can easily be over half your daily usage). Many meals in restaurants (because of the way the cook it, but also because the portions are so big) can have in excess of 2000 calories (for one meal).

You don't need to count calories and keep a journal or anything. And if you start trying to figure out the calories in a banana and how much jogging you need to burn off the banana you've got an eating disorder. But it helps to have a general idea of what's going in and what's being used.