Venting....

Or the opposite, where they try to sabotage you and telling you that you should eat the bad things that you are trying to avoid!!! that annoys me just as much!

How about..."if your advise is so good, why isn't it working for you?" Whether in shape or out, that should give them a complex

Some of this can verge on bullying and it does need you to be brave and assertively push back.

Plan a thing to say that you'd be happy saying, then whip it out if you get an unhelpful comment. "Thanks for your input, but I'm fine" or whatever in a firm tone of voice, with a bit of eye contact and a bit of a fake smile. Push back a bit and see how it goes.

If they respond defensively (which they're likely to do) with a "No need to be so sensitive, I was only trying to help!", try repeating the same thing. Hopefully they'll back off when they see you're not easy meat any more. If not, you might need to be a bit more blunt i.e. "I appreciate your concern, but please don't comment on my eating/weight etc. anymore" or whatever you'd be happy saying.

I was bullied during school but I eventually learnt to push back (when appropriate) and avoid ****-heads (when possible). I've been bully-free ever since!