lol o believe me ive been running my ass of but i stay at the same weight and my recruiter is starting to get pissed off about it
He shouldnt have enlisted you, and MEPS shouldnt have accepted you if you are overweight. If you are overweight when you get to boot camp you will be immidiatley droped from training and put into a remdial physical fitness platoon....Thats how they do it in the Marine Corps anyway.
You need to do more than run. Running will only take you so far, and only if you are really pushing yourself. Your goal should be to run 3 miles in 18 minutes. Run no less than 3 miles at a time and take a stop watch. If you run the same pace everyday you stop burning that many calories and it doesnt do you as much good. Circuit course type workouts are good for building strength, endurance and burning fat. Example: Sprint a quarter mile (and I mean sprint) Do 10 pullups 30 pushups and 30 situps. Do this 6-12 times based on your phsical fitness level.
As far as diet you need to immidiatley cut out: Fast Food, Fried Food, Soda, Sugar etc. Start limiting your carbohydrate intake. Dont get rid of it completley, especially if you are working out hard, but slow down big time on the toritillas, rice, bread etc. even if it is wheat or "healthy." Try and eat a peice of fruit 45 minutes before you eat and eat smaller portions when you do. Dont go back for seconds. Drink plenty of water and stay away from juices, they gnerally have lots of sugar.
Even with doing all that 20 pounds in 2 months is going to be hard as hell and has the potential to be unhealthy for you. Becareful and good luck