I workout twice a day, once for cardio once for weights....and am very good about eating light and healthy throughout the day. I only have a bowl of cereal or banana for breakfast, light lunch (fruit, granola bar, smal salad)...then perhaps a banana before my evening workout. After I get home from the gym then, I have my normal sized dinner. It varies, but it's definitly a normal healthy-sized portion. couple of burgers, spaghetti, whatever. Problem is I feel full right after that, but about 30 minutes before bed, I start to get VERY HUNGRY....mostly for junk food and carbs....so much so that I can't control myself. I'll have 2 bowls of a cereal, some cookies,,,etc. Is this because I'm eating so little during the day,or what?
I feel like I'm only working out this much to maintain my weight + figure, and if I wasn't, I would put on pounds in a hurry!
This is DEFINITELY happening because you are eating too little during the day. When you finally reach dinnertime, you are probably past the point of hunger and so you feel full after a small amount, but once your body receives that food, it gets excited and kicks back in gear and that's why you get hungry again at bedtime. If you were eating enough throughout the day, you would be more aware of when you were hungry and your body would not crave food at bedtime. The fact that you are craving carbs has to do with your blood sugar and feelings of deprivation. I know you think you are eating "healthy" during the day, but you are, in fact, being unhealthy becuase you are not eating enough. Continue to eat healthy foods, but eat more of them! And if you crave a cookie after lunch--eat it. It's a lot better than eating 3 bowls of cereal before bed!
Carb cravings and hunger are typically triggered by lack of balance in the diet. When you eat carb-heavy meals your glucose levels will spike and plummet, leading to hunger and cravings. Even more interesting, the meals you consume early in the day will set the stage for your glucose levels throughout the entire day.
Many people eat carb-heavy breakfasts that are quite deficient in protein. In your case the cereal, milk, and banana is probably about 75-80% carb, 10% protein, and 5-10% fat, which is not good. A better ratio would be 50% carb, 25% protein, and 25% fat - some people do well with 40% carb, 30% protein, and 30% fat.
Another problem that causes hunger and cravings is eating too infrequently OR eating small meals throughout the day and then a huge meal at dinner. I recommend that you eat meals and/or snacks every 3 hours you are awake and none of your meals should be much larger than the rest, especially dinner. If you eat a really large dinner compared to your other meals your glucose levels will spike and then drop about 2 hours later - this will lead to late night cravings, expecially if you do not plan an evening snack (which I recommend).
Let me know if you want any specific recommendations.