Just use common sense, avoid sweets and fats and you will slim down in no time. That means no ice cream, candy, etc. Get your fats from unsalted peanuts, not butter. Make the correct substitutions. Stuff like pizza, fried foods, alot of meats, have alot of fat, and the combination of those and sugars all in excess, will cause unheathy weight gain. Just because you run don't buy into the trend that you can eat whatever you want. In fact, the more you run, the more a better diet is beneficial. A heathy diet will make you feel, look, and perform better, you don't have to starve yourself to lose weight. basically....
eat the correct amount of carbs, eat whole grains, whoever suggested not to is a dimwit
eat alot of fruits and vegetables
cut out things like dips, sauces, fried foods, lots of cheeses, dressings, etc. high fat foods.
eat leaner meats like chicken/fish, instead of a cheesburger
cut out thigns like ice cream, refined sugars, candies, any sodas or beer won't help either
also, try CLIF BARS, delicious, nutritious, and an alternative to candy bars or sweets
don't feel bad if you treat yourself every now and then
if you want to lose weight and be a lean mean fightin machine, just follow those simple rules, I do, believe me its hard but it works, and although I weigh the same as in XC, I am way leaner than I was and feel alot better.