Teens and nutrition problems

[GreenAndMean]

Hey I'm kinda new around here,usually been reading stuff didn't post anything yet so here goes my 1st concern.
As a Teen(18 years old) I'm having a one probably most common problem,how to make your parents buy you good food for your nutrition?
I mean i tried to explain it to mom and dad for X times that i wanna follow my diet which will help me achieve better physique and healthier life,but they just don't get it serious enough...they probably think it's just a phase in my teen years or smth..I can't make them eat egg whites/tuna/beef etc,they buy me that for a few weeks but than again meals start getting crappy,like pizza and cola for saturday lunch(i started to hate that) and since we don't have much money i can't ask to eat something else if they are gonna eat family pizza(because that will hit it a bit on house economy),I do really have a strong enough character to not eat sweets that they buy and leave around the house(i limited myself to 1 banana in a breakfast meal for a cutting diet - even that's probably bad but can't evade it).Now when i think about it i just feel bad because it's like i won't be able to have a good nutrition till i start living alone and buying my own food and that will be in at least 1 year from now maybe even more.
What do you guys suggest i could do to convince my parents?

[bobjack]

get a job buy your own food its nearly impossible trying to explain to them
even when i was 300 lbs i couldn't get my parents to help me they just kept trying to feed me unhealthy stuff

once they start seeing results they will take you seriously

[GreenAndMean]

Problem is that's a bit hard..since i'm still in school and i'm a good student(atm it's summer vacation so i'm kinda free but that's not gonna last forever) and i'm planing to go to a college in a different country,i usually don't have much time for myself except for gym/cardio(when cutting)/studying/nutrition that usually makes up my free time,i go out rarely...still even with nutrition i kept for a few months i did a great progress,so finding a job would be kinda difficult(especially the country i'm living in is in very crappy position atm, a lot of the ppl don't even have job so not many would give it out just like that to some teen) because i lack a free time for it.