The main problem is that sugar is in just about everything we eat that comes in a box, or in a tin, or is frozen. And they put sugar in food on purpose to make people want it even more.
the only way to stop the craving is to stop eating any convenience food at all. To be honest, once you have stopped for say a week, the craving does go away. But it isn't easy. Willpower is needed. You can always come on here, and we will give you encouragement.
there is also a useful ap called myfitnesspal and you can download from Google. You can put your weight and height in and if will tell you the amount of calories you should be eatimg each day and it will even break down the amount of fats, calories, sugars carbs etc.