I just wanted to chime in on this subject. I lost a bunch of weight since I started running, but seemed to hit a plateau lately, so I stared taking a harder look at my diet. I developed a spreadsheet were I keep track of everything I eat. I monitor calories as well as fat, carbs and protein. I am using the Active.com nutritional guide to obtain the correct amounts of each. It drives my wife crazy, because before I eat anything, I have to get my spreadsheet out and compute the values to see if it works. It's almost like a game to see how close I can come. But I may be obsessing a bit.
Anyway, a normal running day for me might be as follows:
Breakfast: 2 scrambled eggs and 3/4 cup oatmeal with OJ or coffee
Snack: Yogurt and an apple
Lunch: Tuna sandwich on wheat and a salad
Snack: String cheese and an orange
Dinner: 4 oz chicken breast, 2 cups salad, low fat dressing, 1/2 cup rice.
I try to shoot for about 1525 calories per day on normal running days since my BMR is 1525 and I still have about 10 lbs to loose. On non running days I cut that to 1025.
I also try to shoot for 51g/day fat, 153g/day carbs and 115g/day proteins.
Since I have been doing this, I am starting to fall off the plateau