How did you modify your calories when you started training for a Half Marathon?

Prior to my training I was sticking around 900 calories per day.  I admit I don't know how to modify my caloric intake now that I've started training.  Today I did a 9-mile long run and used 2 GUs.  Around mile 8 I started to get really light-headed and saw black spots.  In all the years I've been running I've NEVER had this problem.  And then it dawned on me that I had only eaten 200 calories and drank 44 oz. of liquids prior to my run.  So my question is:  How did you modify your caloric, carb, and fluid intake when you started training?  Thanks for sharing!

 I had to up the carbs and moved to counting "net" calories, not gross calories, so I would take the workout into consideration.  I kept a 500 calorie deficit.   

I upped my protein. That's what Dr. C told me to do and it worked. First he had me on 70-90 like everyone else. Then 100, then 120. When I was doing 100, it raised my calories about 100 a day. But at 120, I was up to about 1200 calories. I didn't go past that until I was ready to stop losing.

You should talk to Dr. C and see what he says.