If they are active then yeah, 4000 calories is not at all unusual as a teen.

Easily. From 14-17 I lived on a 5,000 calorie diet and struggled to gain weight, between marching band, PE, shop class, an avid skating hobby, a girlfriend, and growing in height. I could have easily eaten an entire chicken at the time.

Growing takes a lot of calories.

If you're a bad enough dude, a whole rotisserie chicken is only one heart.

Yeah, pretty much.

I remember eating 4000 to 6000 calories a day in high school. I could put away two double whopper meals - large fries, large coke - in a sitting.

Or a 16" pizza, with plenty of room for Jo-jos.

Or 4 big plates of spaghetti, with half a loaf of garlic bread, and salad until there was no more salad to be had.

I was scrawny. Too scrawny for high school sports. 5'9", but I didn't break 100lbs until my senior year.

If they are physically active, yes.