I am an ectomorph - I can eat whatever I want, but won't gain a single gram.
Once I've been interested in how big Ectomorph I am.
So I started eating only junk food for a month (McDonald, pizzas, candies...).
The result has been ridicolous. Instead of gaining at least 1kg, I lost 2,5 kg. xD
So I got a little bit pissed off. I have ordered a proper food menu from a Fitness guy, who had great results.
So my diet began, and I started going into a gym for approximately 45min - 55min, four times a week.
I did workout only with heavy weights, didn't make too many reps. I did also workout only the big muscles such as: Legs, back, and chest.
After one year without progress, I gave up. The biggest joke is my brother is gaining weight like nothing. I'm 21, and he is going to be soon 18 years old.
Within a month he will be heavier than me, even though I am the taller guy xD
At least someone from the family is going look good! hahah
The point is my metabolism is so fucking fast that, if I gain something within a day it's gone.
Whatever, to have at least some strength, I exercise at home 3 - 4 times a week.