What is a healthy diet?

As my BMR declines and I have to compensate for reduced exercise with stricter diet, I find myself more often feeling exhausted on lower-calorie days. I'm never going below 1200, but sometimes when I'm below 1600 I get through the day with few calories, and I've eaten in a such a way that I don't really feel hungry, but something feels physically unsatisfied. Which got me wondering if sometimes I'm not getting enough real nutrients. It's easy to get enough essential nutrients on 2000/day. It's no doubt possible for 1600, and possibly down to 1200, but you have to be more careful and make sure most of the calories come with good nutrition. So what is a healthy diet? I do not have the time and energy to invest in looking up RDIs for all the vitamins and minerals, let alone make up a meal plan that isn't repetitive and fulfills everything, but the simpler models of a healthy diet aren't so helpful. One model I heard a lot growing up essentially says, minimize dairy, minimize carbs, minimize salt, moderate fruit... okay so I'm eating nothing but beans and veggies. That's realistic. The food pyramid model is easier to work with, but it simply doesn't work because the minimum number of servings of everything adds up to way more calories that I'm eating. So, what tests could I apply to my diet to determine if I'm eating healthy?

I'm going to provisionally define a healthy diet as:

- 5 servings of fruits and vegetables a day
- A complex carb and a protein at every meal
- No more than 10-20% of calories from "empty" sources like oils, added sugar, alcohol, and refined or artificial carbs and fats
- At least 1 and no more than 3 servings of dairy per day
- Fish 1-2x a week
- Total meat (fish and fowl only for me) no more than 2-3x a week

I'm of course aware that vegan diets and meat-heavier diets can be healthy, even at low calorie values (and in fact most vegan diets are low calorie by default) but given my actual dietary preferences this seems like a good way to spread out nutritional needs. Now I need to look at my food journal and see how well it adheres to these standards. I think I will need to start insisting on vegetables in dinner no matter what, and also try to have a vegetable and a fruit at lunch because I simply don't eat those things for afternoon snacks - sometimes I don't eat an afternoon snack at all, but if I do it has to be denser than that. Another thing to look at is "empty" calories. If my target calories are 1500, then I should be limited to about 200 "empty" calories.