My Fitness Pal definitely works better if you 'eat back' your exercise calories, as long as you have recorded them reasonably accurately in the first place. I use a heart rate monitor that has my weight/height input, so I think it's pretty accurate. Also, you need to make sure that you weigh food, don't guess it. The difference between what you think a healthy portion of something like pasta is, and what you're really consuming (in my case at least) can be startling.
My weight loss stalled last year for a while, coinciding with the time that I started running. When I started using MFP to track my food, it became apparent that I wasn't eating enough to fuel my runs. A small tweak in the diet (eat a bit more, but keep it healthy) and the weight started coming off again. Now 5 1/2 stone down. So yes, you can lose weight through running .
I have only been running since last summer, and did first my (very slow) Half last weekend. I honestly have no desire to ever run 26.2. I do want to improve on my Half time, but that's enough of a goal for me.
This may partly be influenced by the fact that I have power walked 26.2, twice, and I still remember how utterly boring it was between miles 19 and 24! Also, being such a slow runner, I could be out there for days trying to run a marathon
Alan, looking at the pics I'm pretty sure I wasn't the only one! Confess I didn't do 'hand on heart' over the finish line simply because I was so ecstatic at a/ finishing and b/ being 20 minutes inside my target.