Newbie to running....additicted 
I have lost 2.5 stone since Jan 2012 from running around 5k 6 nights out of 7, but now sometime when I'm running the last mile or so my legs turn to jelly..out of gas. I have changed from 5k one night to say 2.4k the next. As i'm on a diet (Brown rice/pasta..healthy stuff) I only consuming around 1500 cal a day..yep I know that way to little, thats why my question is what portion size of carbs,etc should I be eating at meal times, pre/post run......
Any help or advice would be gratefully recieved...;)