Decision time
What to eat? and how much to eat? are important parts of any diet, and while I think it's good to learn about both you do have another option:
If you're willing to eliminate certain food groups from your diet and focus on others, you'll probably do well without fussing over how much you eat.
Specifically: you'll be unlikely to overeat if you eliminate all foods containing grains or added sugars or legumes or dairy, and base most of your meals on vegetables and fruits and meats and nuts. Of course it's still possible to go overboard with denser foods like potatoes and bananas, and even meat, but it's much less likely if you're sensible about it.
This is the basis of the Paleo approach.
But consider this...
Eating 'Paleo' does require considerable commitment, and while I fully encourage you to give it a go, I think it's still a good idea to learn roughly how big your meals should be, and there are added benefits to balancing protein and carbs and fat each meal. The Zone Diet guidelines are a good place to start to find your balance.
On the other hand...
Even if going paleo doesn't tempt you at all, you may have to to fix or prevent or improve whatever ails you – see if you have any good reasons to go paleo (coming soon).
So if you think you can go without modern processed foods and the idea of measuring foods sounds horrible you can skip this section and head straight over to Paleo food choices (coming soon).
The Zone Diet guidelines
The Zone guidelines are designed to provide a suitable amount of protein and carbs and fat for someone as big and as active as you are.
You can choose how accurate you want to get with this – if weighing and measuring food for a few weeks sounds like a nightmare stick with this simple method, otherwise give the Zone Blocks method a try.