Marathon Training - How many calories do I need?

I'm signed up for my first marathon in May. I've been running consistently for several years and have picked up the pace and miles recently to prepare. I know what I'm doing, but I have one burning question... how many calories should I be eating?? I'm 6 feet tall and currently weigh about 190lbs. I have set my calorie intake to 2200 a day in the hopes that I'll maintain a steady loss of 1-2 lbs a week until I hit my goal weight of 165lbs. I feel that this is healthy and it would benefit me to have less weight on my knees and back as I run. Right now, I'm running about 21-25 miles a week, 4 days a week. The problem is that I have an office job and usually get home late, so aside from my runs in the early morning, I don't do any other workout. How should I adjust my calories to match this?

 Hmm - you should get a heart rate monitor. Mainly for performance - heart rate zone training will make your training for running performance extremely efficient and maximize your performance come race day; but it will also allow you to monitor calorie expenditure on your runs so you have an idea of what you actually burn during your workouts.

 When you're running more than 15-20 miles a week it gets tricky to maintain much more than about 500kcal/d deficit without zone training. Actually, performance and training effect tends to suffer anyway if you maintain too much of a deficit on a distance training program but with zone training you can minimize the detrimental effects.

 Wes will probably drop by and give you a lot more specific recommendations later on, he's the triathlete around here ;)

Thanks for the reply. I actually have a Suunto HRM that I enjoy using, but unfortunately it doesn't have the calorie monitor on it. I hadn't been using it on my runs but I'm sure that I can find a way to convert my avg. HR over the length of the workout into some idea of calorie expenditure. I've just been finding it difficult to  adjust my intake vs. output because one day I'll run 11 miles, and the next I sit on my butt all day, or at least it feels that way. CC estimated that over nine miles of running I burned over 1100 calories, which is great, but I've been restricting myself to "make up" for the following day... if that makes any sense. My health and performance are the most important things with weight loss coming second, but it'd be nice to lose a few in the process :0) I'll look forward to hearing from Wes, as I'm a triathlete myself and could always use a few pointers.

Good luck with your marathon!

If you don't already read it, I would visit http://www.runnersworld.com (site of the magazine). They have a LOT of extremely informative, helpful articles, calculators and tools to help.

I'm also training for a marathon in May.  This is what I have done since I too run 3-4 days a week.  I hope you have a marathon training program that you are following, if not go to Runnersworld (or another website) and get one.  Then you will know how many miles you will be running in a week and then can estimate how many calories you will burn from the runs.  It's a little time consuming but you can figure out about  how many calories you will burn throughout the week and then figure out how many calories to eat daily in order to have the weekly deficit of around 3500 calories for 1 pound of weight loss.  That way instead of eating say 1800 calories on a non-workout day and then like 4000 calories on Saturday because you had a long run.  I hope this makes sense to you.

BTW, what marathon are you planing on running?  I'm doing the Fargo Marathon May 9.

Hey -  Thanks for the reply. That's actually something that I hadn't considered, I'll give it shot for this week or next. I've been using my HRM and then entering my average HR into a formula that tells me how many calories I've been burning. I was surprised because it's far lower than what CC tells me I burn for the same about of time. For instance, CC estimated that I burned about 1100 calories for 1 hour and 20 minutes of sustained exercise at about 11.5 min. mile pace. This other formula took my avg. HR of 144 and estimated that it was only about 630 calories. I figure that's closer to the truth, so I'll stick with it for now. I'm running the Riga Marathon in Latvia. I'm stationed in Germany, so it's easy to get to and I have family there that I've never met. Good luck on your marathon!

Yea...  The only way to run a deficit is to estimate the amount of calories you are burning while running, then religiously count everything you put in your mouth.

When you get your mileage above 10-12 miles (above 2 hours), you are going to need to start practicing eating and drinking fluids while you run (unless you are a sub-3 hour marathon guy).  There is plenty of research on the web, but you only have enough energy for 2-3 hours of uninterrupted running.  You will need to take in gels, sports beans, something while you run so you don't hit the wall ( and fluids to replace what you sweat).

This will complicate your caloric intake and make it more difficult.  It's not impossible.