Do 2 or 3 days of consciously choosing what you are going eat for each meal. If you can do a whole week. Think about the portion sizes, the balance of the plate and then notice afterwards how you feel.
Immediately afterwards notice if you feel overfull and perhaps didn’t stop eating soon enough. Or do you still feel hungry but within half an hour you realise you’re actually quite full.
Following that, what is your concentration like and your energy levels? What are your moods like and is there any pattern to them according to what you’ve eaten? How well do you sleep? Which part of the day are you most productive?
How soon after a meal do you feel hungry again?
And particularly notice what foods you crave or are drawn to – sweet, salty, soft, crunchy?
Just notice. This is the first step to listening to your own inner nutritionist. Your body is a mine of information and you listen it will tell you everything you need to know.