How do you deal with others negativity?

I offered my own tips for successful weight-loss/ new lifestyle for fitness when my family and friends said something like that to me. I dragged them to gym with me and tried whatever I could to make them believe that "they can also do it." But when nothing worked & they recognized their own problems (can't give up on their "blooming appetite," no motivation for workouts, etc.), they stopped acting like that.
I'd think they have no bad intention but just want to know if such human being (who has strong will to stick to the plan and has succeeded) really exists in their lives, and they'd feel shameful for teasing us when they realize how much effort we've put and how weak their willpower is.

Congratulations on your success!

If my friends get this way, just remember that you're probably a lot more satisfied with yourself then they are, and their comments are probably stem from jealousy and not apathy towards your success.

One thing to consider, if they aren't being supportive, are they really friends?

First of all Way to go!! You should be proud of yourself of what you have accomplished. Remember if those people are smack talking let them. Their big mouths are just jealous of what you have done and what you have decided to take control over. Your life and health. We all deal with them, but remember to keep those who are positive and supportive of you around because those are the ones you will lean on more than anything. I've not had to deal with a lot of people who are nasty or mean (putting me down) at all because I've got a pretty good support system from my family, friends, church family and my employees. Just take a deep breath and keep doing what is right for you.