Depends what you do during the day.. Some people are just lucky to have a fast metabolism when they’re younger, but it will soon catch up on them as soon as they get older when their muscle mass decreases and they will have to actually work off what they’re eating if they continue the way they are… hope that made sense…
You can check how many calories you need a day here:
depends on the person and how active they are so thats really hard to answer