It also really depends what foods you are eating to make up the 1400 calories. If you eat low GI foods that release energy slowly into your system, you will get hungry much less frequently. I know that certain foods that take a lot of energy to digest, but have very few calories, end up making me feel hungry! I find that with apples and carrots I am hungry a little while after I eat them. There is a theory about negative calorie foods, which use more calories to digest than they give your body.
Oatmeal is a huge filler. I find if I have toast for breakfast I am hungry within a few hours, but if I have even a modest serve of oatmeal, it keeps me full for hours. The calories in oatmeal are fine as long as you cook it with skim milk or water and use sweetener instead of sugar.
The other big key is to try and eat some form of protein with every meal. Protein keeps you full a lot longer than carbs and it is slower release energy so you won't get energy highs and then crashes (which usually leave you craving something sweet). Adding lean protein such as chicken breast, tuna, low fat cheese, cottage cheese, or other lean meats to your lunches and dinner especially, will help you to feel a lot fuller.
Another trick that I use a lot is filling up on low calorie drinks, fizzy diet drinks or even soda water with a bit of cordial in it, will trick your stomach into thinking it is full. If you have one of those before a meal, you will feel a lot fuller after you eat.
If nothing else works eat diet jelly or add psyllium husks to your food. It is a husk that expands in water, a bit like jelly, and it can be sprinkled on your food to help you feel fuller. If you put a spoon of psyllium in half a cup of water you will see that it soaks up the liquid and turns into a gelatine like substance. It's like a trick to your tummy.
So those are a few tips anyway. The main thing to remember is calories in versus calories out! If you are burning up heaps of calories with exercise then you can eat more and still lose weight! You can get a heart rate monitor that also calculates the amount of calories you are burning during exercise, so that way you can work out your daily calorie expenditure and adjust your diet accordingly.