Kathy brought up this very good question. I too have heard as she, that exercise increases your metabolism even after you finish the exercise.
I decided to do a little checking and here is what I found: it does, but for the average person it only lasts about an hour and results in about 10-30 additional calories burnt, based on walking 30-60 minutes or jogging 20-30 minutes at a speed of 6mph or a mile in 10 minutes. I got this information here---go there if you want to read the whole article. Here is an excerpt:
Is My Metabolic Rate Elevated Following Exercise?
Your calorie expenditure obviously increases above your resting rate when you exercise, with the magnitude of this increase dependent on how long and hard you exercise. One frequently asked question is “Do we continue to burn “extra” calories after we finish exercising?” In other words, does our energy expenditure remain elevated above RMR for a period of time after we stop the exercise, and if so, does it contribute significantly to our total energy expenditure on the day we exercise? Research has clearly shown that energy expenditure does not return to pre-exercise resting baseline levels immediately following exercise. The amount of this post-exercise elevation of energy expenditure depends primarily on how hard you exercise (i.e., intensity) and to a lesser degree on how long you exercise (i.e., duration).
Endurance Exercise: Exercise of the intensity and duration commonly performed by recreational exercisers (e.g., walking for 30- 60 minutes or jogging at a pace of 8-10 minutes per mile for 20-30 minutes) typically results in a return to baseline of energy expenditure well within the first hour of recovery. The post-exercise calorie bonus for this type of exercise probably accounts for only about 10-30 additional calories burned beyond the exercise bout itself. In athletes performing high intensity, long duration exercise, the post-exercise energy expenditure may remain elevated for a longer period and could contribute significantly to total daily calorie burning. Ironically, such athletes are typically less concerned about this “extra” calorie burning and its implications for body weight regulation than are the recreational exercisers. The average person who does considerably less strenuous exercise will likely experience little meaningful contribution of this post-exercise bonus to their total daily calorie expenditure.
While it's not a lot of additional calories, I guess every little bit helps. But it is just a little bit, and one could just as easily eliminate 30 calories a day from his diet if he is averse to exercise. More serious athletes who exercise longer and at greater intensity would have significant additional calorie expenditure. But few of us are serious athletes. And our exercise levels, while tremendously health promoting, will likely not add much to our weight loss efforts.
My point is this: don't think you must exercise in order to lose weight. So many people today who don't have time or are averse to exercise for the sake of exercise don't even try to lose weight because they've been told you can't do it without exercising.
Now, I have one more question...that 10-30 calories...is it included in the calories expended during a particular exercise? Having found out that the basal metabolic rate, or calories burnt just existing are included, I wouldn't be surprised to find out it was.
Note: To those who exercise and are doing well, great, I say. I admire those who commit to exercise and even enjoy it. But that is not me and likely never will be. And I am not alone in that rank. I just want to encourage those who are discouraged-- believing they will never successfully lose weight without exercising. I believed it and it held me back. Now that I know differently I am empowered. No longer am I in bondage to a lie.