I'm practically an identical build to tunnie, but a confirmed 6'4
i fought extremely hard to put weight on last year after never in 29 years being happy with myself, got up to just under 14 stone, from eating right and weight training, then dropped to 11½ in the first 3 months of this year due to personal issues
i've managed to get myself back to just above 12 stone (measured at night after a big poo) but i know i'll struggle to get heavier unless i work at it tirelessly, but the problem is, like many people, those who work tirelessly to climb to a certain goal weight tend to be those who are doing it as a hobby as much as other stuff, ie body builders, and they have to follow such a heavy disciplined method. Since i'm not specifically interested in body building as a hobby, i find it shockingly hard to motivate myself and even to eat right, even though i generally do eat good food
some people deal with emotional issues differently, some eat for comfort, and some lose appetite (me)