Might as well add in my $.02:
Don't forget to balance your meals in terms of fats, carbs, and protein. People say to not snack, but the opposite is actually better. Eat small meals with snacks in between. In fact, the closer in size they are, the better. Your total caloric intake shouldn't exceed a certain amount (given weight, exercise, and metabolic rate), but more meals with smaller portions is a lot healthier than fewer meals with large portions.
One last thing: If you find yourself craving certain things a lot, it may be because of a nutrient deficiency. Follow your cravings. Seriously. Your body knows what it needs. If you find yourself craving particular foods, figure out why your body wants them.
And, again, it could be a very high metabolic rate. There are people out there that actually have trouble getting all the food they need simply because of their high metabolic rate. You say that you eat a lot and are worried about gaining weight in the future. Does that mean you're not gaining weight now? Your body doesn't just start gaining weight after X days of overeating. Weight gain is slow, but it's immediate. If you're not gaining weight now, you won't unless your metabolism slows down.
...Of course, you're 21 now. That was quite an interesting case of thread necromancy... twice. This thread is still relevant for those that think they're overeating, though.
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"Let reason be your only sovereign." ~Wizard's Sixth Rule
I'm working my way up to Attending Crazy Taoist. For now, just call me Dr. Crazy Taoist.