Guess what?
You can eat WHATEVER YOU WANT on a diet!
That's right, you could eat cupcakes, ice cream and pizza and STILL lose weight.
The only caveat is, you would not be able to eat as much of it as you would like most probably.
You see, in order to lose weight, you need to eat below your maintenance calories.
Your body requires a certain amount of calories to maintain it's current
weight (body weight in lbs x 15)...so if you were 150 pounds, that would be
150x15 = 2,250 calories/day.
To lose 1 pound you need to be in a deficit of 3,500 calories. So if
you ate 500 calories less than this 2,250 each day (1,750 cals/day) you would
lose 1 pound each week.
So you see, you could be eating 1,750 calories per day of pizza and still lose weight....the only problem with that would be, 1,750 calories of pizza, is not that much food!
Junk food is REALLY calorically DENSE...so that is why its better to limit it.
So instead of eating 1 pound of pizza and using up 1,200 calories..eat 1 pound of broccoli and use up 154 calories.
Drink lots of water too by the way, 8 or more glasses a day, it will help keep your satiated when you drink it throughout the day.
This all should get you started..if you need a solid diet/exercise program, this will explain things in more detail.