I make skinny fags into beefy monsters, trick is it takes a lot of discipline, which is hard if you don't have a dick head Sgt shoving food down your throat and working that ass out.
OK here's the deal:
People have a base-line metabolism and body weight. Your system will try all it can to keep you there, so you have to force it to stay above base-line for an extended period of time until it resets at where you want to be... like a year of everyday struggle. It is worth the effort, ectomorphs with the right training can get strong AF.
- EAT! EAT! EAT! 6-8 times a day, every day at the same time. 3400-3450 calories a day:
430-450g clean carbs (veggies, sweet potato, quinoa); 145-155g protein in as much variety as you can, but if restricted tuna in a can and chicken (No powder, your poop will just be expensive); 105-115g of fats most of it will come from your protein intake and the rest you can get from omega fatty or flax capsules
- You have to go hard in the gym, I get the best results from my bony troops by working them up to two-a-days: Volume-light weight exercises, mostly body weight in the morning every day but sunday and Big power lifts (Rows, cleans, squats, dead lifts, bench press) each at 75-90% of 1 rep max 4-5 sets after lunch M,W,F, the trick is doing them in different orders and variations every time you pound your muscles. Here is a good body weight routine: http://antranik.org/bodyweight-training/ and one for power lifts: https://stronglifts.com/5x5/#Apps
- T,Th,S after lunch do cardio, no light jogs - Go Hard HITT. I do sprints and rower mostly but as long as its a hard push short burst kind of cardio it'll work.
- Sunday- Stretch in a full range of motion, here: https://drive.google.com/file/d/1Z3aY8b-7eGOca312q4YD5pafa5E0r_sG/view?usp=sharing and do a light wallk or jog.
- Sleep! Set aside at least 8.5 hours every day
It'll be slow going at first, you will get massively strong before you start to fill out, but do this until you get to where you want to be (Realistically 1-2 years) and then you can back off a bit and maintenance will be a breeze.
For being able to eat that much:
Take a zinc supplement