All things relative, laugh at me if you will but I weighed 60 kg at ~21 year old, and 62kg or so at 31. Just to prove I was thin. I put on up to 13 kg in around 5 months. Nothing comparable to what the post describe, but like I said all things relative. But now at 34 I am still 72 and I dont eat anything more. So again ,all things relative, I may still be a puny little 72kg with no definition on my chest. I did manage to put 10 kilos that I kept ever since without any more workouts, and I attest that it worked with squats and eat more EVERYDAY. But as for the regimen, if youre thin and weak as I was;, lol even when I was 75 kg (+13kg) I wasn’t lifting my own wiehgt yet,; maybe 50 kg? I dont remember. Also; when I went to the gym I knew the squat was the only thing I needed to get right. So much so that I was scared to go. I only did 1 series; and maybe 10-15 reps, and only once a week. But all the rest of the time I had to watch what I eat. So yeah squats do work even for someone really weak and thin; with a quick metabolism. Up until then nothing worked for me, going to the gym I put 2-3kg jus tbecause I was out of shape and then it stopped. Also someone “weak” can not do 10 exercises and multiple reps, its pointless. Do the squats and 3-4 others, rest for several days (at least 3-4).