Jamesy wrote:
I do tons of cycling and eat healthy.
Being skinny and having little body fat just means I am in good shape right?
Depends. "Fitness" is pretty subjective. Strongman competitors for example, are really strong, but most probably suck at road racing cycling. However, most road race cyclers probably suck at strongman. Does having low bodyfat make you healthy? Not really, as long as you're under like 20% for a guy you're considered healthy by most standards. Aerobic fitness is good, I guess, but real world it doesn't mean a whole lot unless you can't like walk up stairs or something, just as real world being able to deadlift a lot is largely irrelevant as long as you can carry groceries in the house and move furniture.
The rest is just body image/culture kinda crap that's all subjective. Being 140 with a low bodyfat is probably closer to the ideal being pushed in the media these days. Six pack abs and leanness is generally cared more about than muscle mass these days. If you look at singers and celebs now, you'll see this. Nowadays it's very rare for a guy to have any kind of belly in the media. Back in like the 70s or 80s and before, being "bigger" even if you had a bit of a belly, but weren't a total fatty, was more ideal. Not too many people back then really cared about being "shredded" or "ripped."
Some people care more about being "big" and muscular for whatever reasons. Your brother might be one. As far as girls, it's the same way. Some like bigger or more muscular guys, some prefer skinny lean guys.
Whatever makes you happy. If you're happy the way you are and can handle your life without being influenced by other people's negative opinions about it, then stay 140lbs at 5'9. Personally, at a relatively lean 180ish lbs at 5'9, I wish I was 140, as then I could probably jump higher and be more agile. But, not much I could do about it. Due to my frame even without my weightlifting I'd probably be sitting in the 160s. I have friends that are smaller, like 130-140lbs, and most of them wish they were like my size. But hey, if you're happy, that's what counts.