Calories and how many you eat

You know how they say to never go below 1200 calories because your body can't function without it? Well, what if you had three chocolate bars, a bag of chips, and a piece of pizza and it only added up to 1000 calories. Would you lose weight since you...

didn't eat enough calories or gain because all you ate was junk food?

ok first of all, 1000 calories is less than 1200, ofcourse, and you should increase 200 calories more. lol.
Instead of eating junk food eat somthing like saldas, its waaay healthier and has less calories than junk.
Theres NOTHING wrong with eating three meals per day and you could also eat a little bit of junk food once in a while (just make sure you dont use junk food for survival lol)
Eating 500 calories is NOt okay!! YOU are only 13 years old, underweight, and eats 500 calories per day? Thats just...not right. I hope you know there are many painfull consequences in the future awating for u...only because you forced your body to eat 500 calories at such a young age. DOnt ruin your future because of this...and eat properily

you wud lose weigh babe, you could eat 5 chocolate bars addin up to 1200 cals and lose weight but it is unhealthy and you will luk mingin and get bad breath and eventually you will get fat!!

Forget counting calories. Wonder who dreamed up that one? Just eat lots of salads and fresh raw fruit. It will fill you up and you will lose lots of weight. All junk food does for you is add weight to your body as most of it contains fat, the wrong kind.

you should work out your BMR.
that's how many cal's your body needs per day to function and not go into starvation mode.
there's calculators online.