Eat 1 tin of tuna and 1 apple a day, thats what Christian Bale did :
to this :
But yeah a terrible idea, I'm a student and I mainly eat, rice, tuna, chicken breast 3 times a week, milk every morning, 5 veg/fruit a day thing and drink plenty of water. Though I never seem to put on a lot of weight no matter what I eat. However when I came to China, I lost about 2-3 cm on my waist in a month or so, just from the rice diet and well not eating much generally since the food was weird at first. I think snacking is the biggest weight gain, just cut any snacking out, the only time I ever gained a lot was my first year of uni, didn't have much to do, so snacked a lot.
I hate the whole counting calories thing, who wants to spend their life monitoring every thing. Just be sensible, don't snack, eat the right selection of basic good food and keep up with routine exercise.