Ever felt ridiculous tired without understanding why?
Food can be a sensitive topic when considering it's financial value, its impact on our body, and our sensitivity to our outward image. For the purpose of gauging energy, I'll address food simply as a necessity. Additionally, it may be beneficial for you to add your own concerns to this list. Here a a few ways in which nutrition might be lacking:
Sedentary lifestyles reduce our ability to produce energy for times in which we are require to move around. Not developing your cardiovascular and skeletal muscular systems can cause your body to lose muscle (strength, power, and endurance), lose cardiac muscle (cardiac strength, power, and endurance), reduction of capillaries (oxygenation aka literal energy to your body).
If you wait to sleep until you die, you will unfortunately die quicker. Get real with yourself.
I've said it before, and I'll say it again. Your brain is connected to your body just the same as your heart, lungs, and bones. You may not be able to totally change the structure and function of your body parts, but you can make small adjustments overtime.
When still in doubt, finding resources including a provider could unlock a wealth of information, too!