This post by Canadian bariatric specialist Dr Arya Sharma talks about a study which indicates that exercise is about more than "calories in, calories out". Dr Sharma says:

That rings true for me. When I first started working out, I felt very different - as though my body was operating more efficiently.

Does that sound familiar for anyone else?

Exercise is make or break for me. I've always thought of it as both calories in and out, but also that I then burn calories more efficiently and just feel better the rest of the day.

I tend to think that the truth lies somewhere in between the theory that the calories burned during exercise are all that matters and the calories burned during exercise may not matter at all (the latter is the Dr.'s theory). I think the calories burned do matter, but I also think that the other benefits the doctor mentions also help.

I was one who didn't give much credence to the importance of exercise in weight loss---until September when I started going back to my gym for fitness classes 2-3 times a week. Up until then, my main form of exercise was walking at a moderate pace and bicycling. I was losing weight pretty well doing that, but it seems like when I started those more intense classes, the weight really started to fall off---even after I increased my calorie count. So, empirically, exercising seems to be quite beneficial for me, in terms of losing and maintaining that loss.

I don't think Dr Sharma is saying that calories burned during exercise don't matter at all, just that they don't matter as much as is commonly assumed.

I understand that this is yet another weight-related issue that medical science doesn't fully understand. It would also make sense that the effect is different for different people.

I get a great physical feeling from exercise - I feel lighter, healthier, more limber,it will make a headache go away, it can settle my stomach if it is mildly upset, gives me more energy, makes me stand up straighter, and on and on. I don't think for me though that it really makes a difference from a calorie burn standpoint. Either I don't burn as much as the calculators say or I am one of the people that the burn doesn't impact. I can exercise for two hours a day seven days a week and burn hundreds of calories every day, but I will swing up in weight if I go up 100 calories over maintenence level. I know some people, DH is one, who can exercise a little and see a big change, but for me it doesn't happen.

Edit - now, I look much better from exercise - I'm shaplier, my muscles look better, I've reshaped myself and dropped sizes. So it does have a positive impact.