The "Health at every size" movement it terribly dangerous. It strikes me as one of those normal movements that started with a simple, innocuous, and correct request, "Don't needlessly be a dick." but, it expanded in to false declarations that are fueling and celebrating unhealthy behavior.
I can't help but notice that the overwhelming emphasis of HAES is on obesity while mostly ignoring the opposite end. When I was growing up, I remember seeing a lot of horrifying things being said about Keira Knightley for being too skinny and falsy accusing her of being anorexic. Maybe that's why HAES won't touch the other end of the spectrum; or, maybe because they're afraid to touch something that we know is an eating disorder; or, maybe it's because we all know that people would see through the bullshit if Cosmopolitan published a cover featuring an anorexic woman with the caption, "This is healthy."
Of course, there are ways to be healthy in a wide variety of sizes. A man who's 6'1" 285 is classified as obese by the CDC; Aaron Donald isn't out of shape. We're also not talking about professional athletes 99.9999% of time when somebody is that big.
None of the faces of this movement are people with BMIs that show obesity who can show off their six packs.
Now, what a lot of these spokespeople try to say is that they currently don't have any ailments. All I can say to that is, "No, you don't have any ailments now." It's the same thing that I was telling myself about my drinking, "I've put on a couple of pounds; but, I feel fine, my livers fine, my kidneys are fine." Yep, it was all fine until it wasn't. Telling people that being obese is healthy is like telling alcoholics that alcoholism is healthy.
Of course, be kind with people. Being mean and shaming people isn't helpful. Lying to people isn't healthy either.
If you notice a friend, who was already 5'2" 110 dropping to 85 and noticing that she's never eating food when you go out, you're not really a friend if you don't raise concerns about your friend's health. The same goes in the other direction.
Kind people want others to live healthy, full lives. Lying to people about how healthy their habits are in order to avoid awkward conversations works against what kind people should want.