[pessimizer]

There's absolutely no necessity to shame anyone for being fat. You can be concerned about it with your friends and loved ones, and express that concern if the relationship you have is of a character where you're busybodies about each others' health. There are very few people in your life who would appreciate or desire that criticism from you.

The people being told to shut up about it are usually abusing strangers or enemies, and feel very abused and targeted for being criticized for targeting and abusing people. If you were talking about being fat with someone you obviously care about and cares about you, they'd take it in that spirit. If you shamed them for it, they'd hopefully end that fucked up abusive relationship. The only thing I would ever shame a loved one for is their abuse of other people. Otherwise, I want to lift them up, not tear them down.