Social justice warriors are often mostly just annoying and obnoxious. Sometimes they, however, succeed in being more than just annoying. Sometimes they can get people fired from their jobs and shunned for life, for instance.
However, there are also some things where modern social justice can be dangerous on a massive scale. One of them is the attempt to normalize obesity.
There is a part of social justice activists that promote the strange idea that "ideal weight" is just a cultural artificial construct, and essentially just "fat shaming". They complain how the media portrays an "unrealistic" body image to people, by using skinny and fit people as this "ideal". These social justice warriors seem to think that there is no difference between people of different weights, and that idealizing one particular weight is artificial and detrimental. In other words: There's nothing wrong in being overweight.
But the thing is, this isn't a body image issue. This is not about aesthetics. This is about health.
Obesity is a leading cause for many deadly ailments, such as diabetes, coronary artery disease, and some types of cancer. Fit people close to their ideal weight are much less likely to suffer from these diseases than overweight people.
By telling people "you are fine as you are; do not feel ashamed, be yourself", they are essentially telling them "do not worry about your health, do not even try to improve it; keep living an unhealthy life that's likely to kill you much sooner than needed".
Of course some people will immediately object with the old tired "but this and this person was obese, and lived her entire life without any health issues". Sure. And some people have survived the bite of a rattlesnake. Does that mean that rattlesnake bites are not dangerous and you shouldn't worry if a rattlesnake is near you? Are you willing to take the risk?
Obesity is becoming a pandemic in the western world, and it will have its consequences. We don't need these jackasses encouraging people to not worry about it. That is literally lethal advice.