I learned this from dad.
The appetite will tell you what to eat and how much. This is how you best know what nutrients your body currently is wanting. The simpler you keep your food, the better it works.
Try eating some raw sweet corn on the cob, next time you're hungry for it. Guarantee you, you will feel terrible if you do not quit right when your appetite says.
Try figuring out when to quit next time you are hungry for lasagna. I used to like it, but I found that I felt exactly the same after the 10th serving as I did the 1st.
Since I rely on my appetite, I don't pay much attention to eating the same kinds of breakfasts, lunches and dinners every day. I have never said, "Okay, time for lunch - I need to make sure I have so much from this group, so much from that group, .."
and so on. You don't need meat every day. You don't have to have this with that.
I never measure food or count exchanges, calories or carbs. I am aware of the carbs, however. In the beginning of my illness, I carefully measured and counted carbs. Once I was familiar with them and the foods that carry them, I was able to just play by ear. I know what a Rome apple is going to do to me. Etc. But the prevailing force in how I conduct my meals is my appetite, not a meal plan.
But no one with a human brain is perfect in following their instincts. So there are safeguards. You have to know what foods are dangerous, what some people call "red light" foods - foods that you have a tendency to lose control of yourself in eating. And there's the time limits I try to stay within. When you have a brain, you have the responsibility of using it wisely; you can't just pretend you're a dumb animal and only follow your "instincts," because your unwise brain will be tainting the instincts to some extent. Well, practice makes perfect, they say.
Since we eat food produced in less than ideal conditions, we may need supplements. Supplements may affect the appetite's performance and may be over-consumed. I don't know. I use supplements. I play it by ear. It's not a perfect world.