You know what's worse for people than being fat? The constant shaming and criticism from other people, the feeling that you're not good enough, the self-loathing that can manifest for some people. That stress and mental suffering is very, very unhealthy and dangerous.
Also dangerous is that when you are fat, doctors are reluctant to treat you for anything else. So, e.g. you go to the doctor with a chest infection and they're like, "Yeah, you should try to lose weight first". People are denied medical treatment for being fat.
This is much more dangerous than "obesity". Furthermore, the links between "obesity" and other illnesses are not always well-established (despite being presented in the media as such). I might hypothesise that the reason why we see unresolved health issues in "obese" people
is that they don't actually get adequate medical treatment for illnesses. Also, there is plenty of evidence that diets don't work, that they ultimately result in more weight gain, reduced self-esteem, and more money for companies like Weight Watchers.