It's totally doable, I'm living proof of that. Everybody is different so you have to find what works best for you, but here's a rundown I what has been working for me.
1 hour cardio pretty much daily (4-6 times weekly)
2 servings grain based carbs (limited to 200-250 calories max) per day
3 servings of fruit per day
4-7 servings of low-fat, low-cal proteins per day
8 glasses of water + another 8 oz for every 10lbs you want to lose. 64+56 = 120oz/day to start for you.
9-10 servings of vegetables daily (fresh or fresh frozen)
On top of all that I try and keep carbs at less than 50% of my intake, proteins near 40%, no caffeine after 1:00pm, and no eating after 7:00pm.
Starting weight: 244.6 lbs. 10/01/09
Pounds lost: 80.6 lbs
Current weight: 164 lbs
Goal weight: 120 lbs
Weight to go: 44 lbs
Goal Date: 1/1/13