HAES is a concept that’s become popular in the last few years and it stands for Health at Every Size.
I’m now going to explain this to you using very pedagogical pictures that I’ve drawn. And while I have many, many talents (including speed reading, Trivial Pursuit and putting together IKEA furniture) I can’t draw.

This is a person. This person has a body and it looks a certain way. In fact, this person happens to be thin. That is the one thing you can tell from this picture. (or if you saw this person in real life.)
This is also a person. With a body. This body is fat or perhaps obese. Maybe even morbidly obese. That is also the only thing we observe here. A fact.

Here’s a third person with a body. This body is somewhere in the middle.
We don’t know anything about the habits or the lifestyles of these people. We don’t know how they eat, if they ever exercise, if they smoke or their medical history. Nada.
That is, we have NO WAY of knowing if they are “healthy” or not.
What I’m trying to say here: Weight is not a way to determine if anyone’s health or not. It’s also not a determinant of their habits.
It’s impossible to look at a fat person and say that he or she is going to get diabetes and die early and has never set foot in a gym.
It’s impossible to look at a thin person and say that they probably eat a lot of vegetables.
Think about it. You probably know a thin person who never ever exercises and brags about how he/she can eat anything without gaining weight. Is that person living a healthy life?
BMI and such measures are rubbish.
Health at Every Size is about healthy habits rather than weight. Moving your body, eating a well-rounded diet, instead of staring manically at a scale.
That people are more than what they weigh and that looking at someone is not a way to see if they’re healthy or not.
Links:
Haes Commnity
Kate Harding
Linda Bacon
Body Positive
Dances with fat