Eat lots of green vegetables...They build up your immune system and help lose weight.
Watch what fruits you eat...Some have a lot more sugar content.
Cantaloupe is good and berries (like rasberries, blueberries...)
stay away from sugar & white flour.
I heard a saying once:
"if it's white...It's not right"

:p best vegetable = broccoli, sweet potato, tomato, carrot, spinach
best fruit = apple, berries, citrus (orange, grapefruit), grapes
best grain = oats, whole wheat
best protein = soybeans and related foods (tofu, tempe)
best fats = nuts, seeds, olive oil, avocados
best dairy = yogurt (plain, no added sugar)
best sweetener = blackstrap molasses

these are the results of reading alot of nutrition books and also my own personal preferences. You can eat this stuff all day and not worry about calories, because the fiber will fill you up and your body will feel satisfied since its getting all the nutrients it needs.