Hi G.,
I am 35 and just noticed the same problem. This is how I am tackling it (and it's working over time):
1. Eat at set times, 5 times a day. I wouldn't exactly "graze" as someone has suggested. It's not about eating ANYTIME you're hungry; it's important to teach your body when to be hungry and when to satisfy the hunger. So three meals (breakfast, lunch, dinner) and two snacks, mid-morning and mid-afternoon. Be sure each meal has protein and vegetables (you didn't mention if you have any dietary restraints/issues like vegetarian, glutten-free...). In your snacks if you can get in calcium like a yogurt or a bit of cheese or milk, and fruit or veggies.
2. At mealtime, serve yourself a little bit less than you actually think you want to eat. It will probably fill you up all the same and you'll eat a bit less than you would if you served yourself more, which you'd probably finish by inertia. Most of us have a "clean your plate/don't waste food" mentality, so we finish everything to the point of being stuffed. Not good for us. Serve yourself less!
3. As much as you can, don't eat outside of these set times. Even if you're hungry. This is how you lose weight! You won't go into starvation mode just because you don't eat every time you're hungry, provided you are getting the proper nurtition (which, if you do as above, you will). A lot of diets sell people on the idea that "you never have to deprive yourself." Perhaps after a while your body will learn never to be hungry outside of the set times but that hasn't happened to me yet. Keeping in shape means self-discipline. If you do get hungry, try to drink something instead of eating. Such as coffee or tea or infusion. If you do eat (if you experience a drop in blood suger or are just tooo damn hungry!) as much as you can make it something healthy. A granola bar, for example.
4. Stay hidrated. Water all day long, at least a liter and a half a day.
5. Let yourself have treats now and then. For me this is the easiest to follow!!! :-) If you have the willpower, eat the smallest size of something or split with someone so that you don't feel guilty later. Treats are meant to be enjoyed after all, not about feeling guilty.
Good luck, keep up the exercise which it sounds like you have under control!