One way to look at the body is as a rickety contraption barely able to withstand for a short while the twin ravages of chance and entropy. But another way to see life is as being sculpted over time and encouraged by this "chance" and this "entropy." The latter viewpoint asks us to participate by aligning ourselves to these realities, whatever they turn out to be.
Sometimes these realities catch our attention in a teaching moment. Other times, we would like to interrogate these realities and see if they can answer a fairly simple question. One such question is "How shall I eat?" Another is "Does it make any difference how I eat?" We can design an experiment to answer the latter question but the first question is too broad and the true answer might be highly detailed, so that what little we might learn has no context nor meaning.
So, I will provide a suggested context which may not be appropriate for you, but may help you organize your thoughts and feelings about nutrition.
The best default diet is a very low carb ketogenic diet with only 35 grams or less of non-fiber carb and that uses coconut oil as the predominant fat. Blood sugar issues disappear, cognition may be enhanced, and a surprising number of symptoms miraculously go away. As the weeks wear on, my experience is that muscles cannot be depended on to exhibit strength or endurance.
The second best diet is a low fat, high starch, minimal fructose plan. Muscles come to life with immediate strength and endurance, but unless you are maximally physically active, each meal becomes a metabolic emergency as the body tries to store the toxic glucose even though muscles and liver don't need any more glycogen. This leads to higher levels of inflammation.
The worst diet is moderate fat, moderate carb. Although the carb level may match the body's need for glucose, the higher fat level causes insulin resistance so that one receives the worst of both worlds: muscles don't feel particularly replenished, and symptoms of poor blood sugar control and inflammation appear.
What if we eat ketogenically while we deplete muscle glycogen and then have a low-fat, high-starch meal periodically to replenish muscle glycogen? This is what works best for me, and it was interesting to figure out exactly what the period is, and to feel the whole experience consciously. For instance, I can tell my glycogen is replenished satisfactorily because my posture is automatically better--the back muscles are stronger. If I replenish glycogen with the high-starch meal too often, I get depressed or have symptoms of poor blood sugar control reappear, such as tooth sensitivity.
One way to do this is to plan meals around a core set of foods that provide the right amount of protein, whatever that turns out to be, and all essential nutrients but with the fewest calories--that is, minimize both fat and non-fiber carb. Then one can add either coconut oil, perhaps as part of a blender concoction, or one can add starch, such as brown rice or potatoes to get what has been determined to be the correct calorie level. Same basic meal but there are two manifestations depending on how the muscles feel.
This is my basic plan, and although I change it as circumstances warrant, for me it is the best plan to feel well and solve the practicalities necessary to have all foods on hand for either the ketogenic or high-starch meal.