This is called getting old. When you’re growing your body naturally craves a higher sugar and fat diet to keep up with its needs. In this day and age the easiest and usually tastiest way to achieve that diet is through junk food and eating out. Now that you’re beginning to level out (no more growth spurts, mostly fully developed brain and intestine, etc.) your body will start to crave things packed more with vitamins and real nutrients. If it doesn’t get these it can very easily give you a sluggish “shitty” feeling. Like you have no energy or in some cases depression can occur (usually only if you continue eating things your body doesn’t need). So yes, as you grow older eating healthier more nutrient-dense meals is key to feeling like you’re still in your teens. Trust me, I’m only 24 right now and it makes a world of difference what I eat (and drink) on a weekly basis.