I know exactly what you mean on "eating requires energy and can make you feel tired". I get this too, and what avoids it is to eat as cleanly and naturally as

I know exactly what you mean on "eating requires energy and can make you feel tired". I get this too, and what avoids it is to eat as cleanly and naturally as possible - whole plants, no processed carbs, no salt and oil and sugar. I believe the "eating makes you tired" is a hibernation reflex. Mammalian bodies are designed to pack on calories when food is plentiful in order to survive an upcoming winter. The tiredness is for the body to process the calories into stored fat. Of course, with modern technology, there is no such thing as that food winter, and we never deplete what we had the instinct to store.