The last thing you want to do is run everyday. Firstly, you'll pick up injuries. Secondly, the best way to lose weight is to mix up your training. If you are a member of a gym, use the cross-trainer, bike, rower, swim and also weights (light weights and high reps best for losing weight rather than building muscle). If you're able to train everyday then train at a level that allows you to recover for the next session. A 1 hour run at slow pace will be much better for you than running hard for 30 mins. Hope that helps.
I cannot believe the arrogant attitude of some on this board. I ran London this year. It was my first marathon. Finished in 4hrs 11mins. I never stopped running and I was in agony the last 6 miles. For someone to suggest that that wasnt an achievement is unbelieveable. I had hoped to break 4 hours but, with the heat on the day and probably lack of sleep due to nerves (only got 3 hours) it wasnt to be. I'm not dissappointed. I gave it everything I had.
Everyone had their own objectives and we all started our training from a different base level. Whether you finished in 2hrs 43 (like my brother who's been running for 30 years) or 6hrs 25 (like a friend of mine who lost 5 stone since Sept training for it (and has a bit more to lose)) well done. You completed 26.2 miles. You deserve your medal and you can call yourself a marathoner.