How do you respond to someone who points out to you that you've gained weight?

Yes, especially here in the middle finger, see?

"Years ago I had a colleague who was seriously fat but such a good dude. At some work related function, some monster walked up to him in stiletto heels and started to ride him because he was dogging the refreshments. Not missing a beat, he told the monster that she would "never have to worry about Anorexia Nervosa getting me!!!"and went on to the chips and dip.

Only a small minority of overweight people are unaware of their condition, and they're in a coma or unconscious for some other reason.

The swine that pointed out his weight was insensitive and should have been guided to go have intercouse with themselves.

You can take the high road and not respond to a rude comment. OR, you can get down and dirty and point out something homely about them and what they can do about it like suggesting they wear a paper bag over their head, depends on who made the comment, a peer, friend or somebody who simply knows who you are, and what mood youre in at the time.

It depends on the person. It is rude to point this out, but at the same time, some people just have no tact. If you want, you could point out one of their imperfections or character flaws and see if they get the point regarding how rude they are being.

The person who said this for you might have honestly been motivated by a sincere interest in your health. Even though this remark wasn't particularly tactful, there is no reason you need to return a tactless reply. Something like, "I appreciate your concern," might do.

Just turn and walk away and don't talk to such toxic people. That happened to me before and that is what I did. The lady died soon afterwards but she hurt me and said it in front of anyone standing there. She said hey you got fat! oh well. I guess that is what marrying her grandson did to me. But I still look good.

Just recently someone made a comment to me (not about my weight... it was something different). My standard response whenever someone points something out about me is this:

"Huh... I never noticed before. But thanks for making me that much more self-conscious about myself than I already am"

You could say something like..."My gosh, I feel like a movie star with everyone voicing an opinion on my personal issues" and then give them your best smile and walk away.

My weight goes up and down all the time and when someone says that I just give them a sarcastic look and just say thank you

I just give them "the look" and then change the subject. It's beyond rude, none of their business, and it doesn't deserve for you to justify/excuse/explain or even comment.