The first step is to understand what biological processes affect hunger and energy levels. I'm going to butcher the details for simplicity's sake, so please do further research yourself.
You get hungry and/or tired because your blood sugar is too low, and your cells are craving some energy. So you eat, and your blood sugar rises. Your body then produces the insulin to turn that blood sugar into usable energy in your cells, and you regulate to a normal, satiated, energetic state for awhile, until your blood sugar starts to drop, and you become hungry and/or tired again.
The reason snacks are recommended is because it's not just what you eat, but how you eat it. If you spike your blood sugar (e.g. eat a bag of candy), your insulin will also spike, reducing your blood sugar to "I'm hungry and tired" levels again before you're actually in need of more food. It's a regulatory system, so your body overcompensates when you introduce a shock to the system.
It will take you time to adjust to a better system, because you're purging your habitual behaviors, and your body will resist this change even though you know it is beneficial.
I highly recommend looking into the "south beach diet". The only "diet" part of it is the first two weeks, when you effectively quit simple and refined carbohydrates (which break down into blood sugar far more quickly than fats and proteins, and therefore create spikes in your regulatory system), and break the addiction you have to an unhealthy cycle. You'll have to force yourself to eat protein in the morning, eat when you're not hungry, eat vegetables, and generally retrain your body with all the normal "diet" behavior.
You only have to do this for 2 weeks (and it's not too hard to do any diet for 2 weeks). After that, you've effectively returned your system back to a normal state. Then it becomes about re-introducing a lot of the things you enjoy, but approaching them with a full understanding of how your body is processing them.
This, of course, assumes your problem really is nutrition. Sleep cycles (and deprivation), exercise, light exposure, and more serious medical conditions (see your doctor, I am not one!) can also be contributing factors.
I know you didn't say you wanted to lose weight, but I want to share that the south beach "diet" (really, "lifestyle") helped me lose weight and, far more importantly, keep it off for the past 3+ years.