Been talking to a couple of families who are going through the same thing, as we are also (2023 son is 6'0, 155lbs). One family said the program they are training with has their son on a 4,000 calories a day diet. The son has gained 7.5 pounds over the past 4 weeks. Another family, whose son is a skinny 2021, said their doctor said the son's goal should be 6,000 calories a day.
But what we are finding as an obstacle with eating is being back in school and all the restrictions they have at school because of COVID. The kids aren't allowed to eat unless they are at lunch and at the designated lunch areas. So from 7:15am to 2:30pm, lunch is the only time they get to eat. So we have been packing huge lunches but it's still an issue. My son said you can only eat so much in the short lunch period without feeling sick in his next class.