It would be the same way if you suddenly made a lot of money, started driving a fancy car, and began dating Anna Kournikova. A lot of people would pretend to be happy for you, but actually carry around petty resentments. A lot of people don't seem to like it when you "break away from the pack." If all your friends want to stay in the same home town and you dream of getting good grades and going away to school, it might be the same way. "Fuck you loser, you are dedicated." Well, fuck them.
For some reason I look "built" even at 170 lbs (I was 152 when I started lifting at 23, had been 140 when I graduated high school), probably due to my height (and small family so I look big by comparison), so I've had minor comments here and there over the years (sometimes by girls hitting on me, which is the good part). Anyway last year I was around 180 and this looked big for me, and people like my old friends, my chiropractor, etc., would come right out and say "you look really bulky 'up here'" or whatever, sometimes they even make some stupid bodybuilder pose and go "grr" just to make fun. Now I'm 192 & growing at a low BF and obviously some kind of bodybuilder type so they say nothing. (Considering I'm 35, most of my friends are starting to look like fat-asses so it's even more noticeable.) The only guy who never really said anything is this friend who is about 6'7" with a huge lantern jaw (actually he looks a bit scary) and a kind of "throwback" rocker dude hair style. I guess he is used to being looked at with envy or being made out as a freak or whatever so he is actually happy to be with someone else who understands. I used to be scared to death of this guy because he was so damn cool, now I play golf with him and challenge him to fights all the time (which makes him laugh).
Put it this way, when you're in the process of surpassing people in some way or kicking someone's ass, they whine a lot, but they quieten down once the process is clearly done and you've left them in your dust.
Understand this human nature and be humble and gracious and people will adjust to your new life and new size. Just count yourself lucky you found this lifestyle! Me and most of my friends used to think alcohol was the answer to pretty much everything. After age 30 I figured things out a little better. Coulda saved a lot of headaches learning this sooner.