Not too much

How much are you really eating.
When you eat that cereal in the morning do you need a bagel 15 minutes later.
No you don't. You need to eat a balance of carbs, protein and fats.
The food needs to have nutrition to it. If you eat a high sugar or carb food without adding the fat and protein to it your body says okay stop teasing me, I got a taste but no way is it going to sustain me for more than a few, give me food, real food, food that fuels me. It kind of like giving a car starter fluid when it is really out of gas. You need good sustainable fuel.
Add a boiled egg, with an apple to your breakfast cereal. Or have yogurt, berries and a bit of granola. Stir an egg into your serving of oatmeal and make it oatmeal custard. How about a Canadian bacon sandwich with lettuce, a slice of tomato a teaspoon of mayo on a whole wheat emglish muffin.(watch for bad oils and trans fat). Don't let the front of the label sway you, read the label on the back with the real information on it.
Remember fats are not bad, we need some at everymeal just choose the correct fats.
Eat a sustainable breakfast and you won't need to eat again for 4 to 5 hours.
Or if you are on a 2 to 3 hour schedule, choose a bit of protein with each mini meal.