The type of food you eat has an enormous effect on how much you want to eat. For example, if I have oatmeal in the morning, with a cup of fresh fruit and some nuts, I'm totally full until lunch.
Sugary foods and those made from highly processed carbs will generally cause you to be much more hungry, even though they're high in
calories.
At your weight, eating 1200
calories a day is definitely NOT the answer!