One area where it's hard to deny that political correctness crosses a line from "Just don't be an ass to people." to demanding that people lie is the body positivity movement. Basically, we've gone from asking people to be kind when raising health concerns and suggesting that losing weight may be a good idea to actually peddling the idea who are dramatically overweight are healthy.
One argument that I hear these activists use fairly often is that despite being overweight they still don't have any of the ailments associated with obesity. Well, you can say that until it stops being true.
I spent years shoving hard liquor down my throat and feeling fine. I put on a few pounds; but, I was never outside of a healthy weight range. I never convinced myself that my drinking habit was good for me; but, I did convince myself that I wasn't causing any real damage until I woke up one morning feeling like my liver was trying to turn itself inside out and I ended up in the hospital for a week.
You're healthy until you're not. I'm glad that we haven't come to the point where major magazines are featuring people chugging whiskey straight out of the bottle and saying "This is healthy." But, there's really not much of a deference between that and saying that obesity is healthy. Bad habits will eventually cause problems.
Be nice in raising concerns; but, don't lie to people.