I'm the text book ectomorph with a high metabolism. The My Fitness Pal app is great for keeping track of your daily caloric intake, but here's really all he needs to do:
1. For workout
https://stronglifts.com/5x5/ <- follow it to the T
2. Without all the hows and whats of the BMR and TDEE calculations, he should be eating 3k calories a day consistently. The easiest way to get 3k calories is GOMAD (Gallon of whole Milk a Day). He will gain fat % which is a problem for me but at 4% (is that even possible?) he needs it.
Do both of the above for 3 months, then take a month off from the workout and then start again if needed.
Back to the original thread, I'm following the above routine to put on mass before cutting because I'm too damn skinny to cut. Skinny fat to be more accurate at 16% BF when I started, now 18% and it'll keep going up until I stop bulking. For me bulking means 2000-2200 cal a day (for my age and activity level).
Unfortunately I fvcked up my right arm by going overboard with the barbell curls because I was finally able to bench press my own weight for 1RM. Got too c0cky and thought I could curl 90lbs for 5reps (up from my usual 75lbs). Now my tendons are torn and not healing, I might have to go see a sports medicine dr.