Well okay .I used to weight 283 pounds . As of yesterday, I finally weight in at less than 200 (199), yay! Well ever since I've been losing weight , I started noticing obese people more and more . I kinda have the urge to tell them how much their life might change if they lose weight . And that losing all the weight is definitely worth it . IIN?

As long as you don't start pushing your opinions on over weight strangers then i'm sure you'll be fine. It doesnt hurt to give a bit of advice to a friend or family member if they complain about their weight and you feel your comment could benefit them...but just remember to not turn into one of those people that constantly comments on people's figure and act obsessed with weight etc lol, which i'm sure you wont.
p.s congrats on losing the weight btw. I'm sure your a lot more confident and happy now! I've joined the gym! on a mission to lose a few pounds my self haha!
Of course it's normal. Being in shape makes you feel better and now you want to share that knowledge. I just don't know how people would take it. Overweight people tend to get highly emotional about the topic. Maybe you could start a blog? Anyone who interested will listen. And, you'll save yourself from the negative reactions.