No one knows the absolute answer for all of us. And it's very hard to tell what's at cause for those just starting out in there growth after puberty & teenage growth spurts.
Most of us, in our older years, if we don't have the rare & so admirable "lean genes" (passed down in our family - if your parents aren't naturally lean, chances are there are no miracles happening for you, it's just temporary) or bodies will start to show different & unexpected results ('cause this is your first time in the growth process of life).
Look at all of us older guys & ask us what struggles we've gone through to make up for our wild, excited & (what we think is) the unique results we thought were happening because we were special, & we had some amazing handle on how life works, & how our body & mind works.
It's common during human development (especially boys/men) to think we're possibly "the one" (I think it's called, "the messiah syndrome), and we have some special "powers" & abilities beyond everyone one else, or we "have it all down", or, "handled".
You might actually have something, but 80 or more percent of us after our late 20's, after growth hormones have done whatever they're gonna do, have started to show signs of struggle reflective of our "unique recipe" of how we've some how singularly come across the secret miracle to doing it all better then anyone else has ever come up with, with lasting results.
I used to tan everyday thinking I figured out how to do it so I wouldn't damage my skin like those who did, smoke cigarettes as though I was the invulnerable one to it's dangers, & get wasted everyday to prove I could live through it better then anyone else has ever done (or die a hero because I beat old age & conformity). Now, in my 50's, I didn't get cancer or die from getting wasted, tanning or smoking, but my liver & mental skills have suffered a bit & my skin has lost it's elasticity, & my body's natural healthy cravings & needs have been altered so much I can't really tell what it naturally needs (which happens with fast food & other overly processed foods, by the way).
We are all unique, but not all that much different. What's recommended by most experts for all of us to follow as healthy is a good guideline to start with, & slight modifications, depending on your family genes and your personal body & lifestyle desires, can make the valuable difference in creating & maintaining what outcomes you want, but if it's drastic, look at & ask us older folk, from our own actual experiences (not what we THINK might happen) how our habits could have possibly taxed us in the long run.
I, personally, since the age of 16 admired lean skinny body types & tried so hard to come up with "the secret" to living skinny. It wasn't naturally in my genes, so I knew I needed to alter my habits. I reduced my calorie intake & that worked for awhile during my late teens, early 20's, but after awhile I was feeling too hungry & gaining weight. I added diet pills, but that wasn't realistic for a lifetime habit. I added exercise but didn't have enough energy, and the pills were making it hard to sleep, so I was extra tired & my heart was racing. My metabolism was messed up, along with other things thet would have benefit my intended outcomes & desires, but I didn't know I was defeating the purpose.
It took me years (& still pretty much working on it) to evolve my habits from unrealistic to much more realistic, and it's all looking more & more like what most experts have been learning through out the years: eat the best nutrients for your body to work at it's best, have at least 8 hours of sleep each night, keep at least an hour's worth of physical heart elevating activity available each day, drink plenty of water, eliminate stress by loving yourself & those around you with understanding & compassion while you continue to practice creating a healthy you, and building on the opportunities thet really light you up (never regretting where you are & what you don't have), and for those of you who want bigger muscles, add strength building workouts.
[Even for us older folk, it's our first time going through all of this. We've never been older then we are now, but we continue to get older then all the new kids born & we all try our best to figure out how to do it best. We older folk have done it before you, but we don't necessarily know any better, and we still don't necessarily know all, though we might think we do.]