This is me elaborating. TL;DR at the bottom if you don't want to read the wall of text. It's really quite simple.
Maybe I shouldn't have used the word wrong in my FB comment. Misguided might be a better term, because the author is talking about things she claims not to understand regarding the fat acceptance movement. I'm giving her the benefit of the doubt and assuming she doesn't understand because she's never BEEN fat, saying she's a "normal" size (her quotes). What she really means is she's a socially acceptable size, which is not the same thing. The movement isn't for or even about her. She doesn't understand it because she can't conceive not hating herself if she were fat.
I'll address her points one by one. Again, TL;DR at the bottom.
1. America is extremely accepting of fat. America's food, marketing, and yes even diet industries are likely the driving force behind a good portion of our obesity, but America is NOT accepting of fat. The author downplays the prevalence of negative stereotypes, staring, bullying, and crude comments, possibly because she's never seen, heard, or experienced them herself. She may not be aware of the constant barrage of well-meaning and not so well-meaning comments people of not normal size have to endure on a daily (and sometimes hourly) basis. Random strangers judge and try to dictate what a fat person eats, wears, and how much or little they move, without a single idea who that person is or what their personal or medical history might be.
She doesn't mention people of every size participate in the behaviors she cites, nor that body size and behavior are two entirely different things. Instead she implies all fat people are fat because of lifestyle choices. She doesn't mention that SHE is in fact not accepting of fat, and the fact her article went viral is an indication of how rampant that attitude is in our culture. She also doesn't mention that somehow her attitude gives her the right to judge, dictate to, and discuss the acceptance of anyone with a body shape she deems unfit and outside the spectrum of "normal."
2. Body Positivity should include health. This point assumes it's impossible to be healthy when overweight, fat people have absolutely no healthy habits, and being fat is a choice. Body Positivity is more than loving the shape you're in. It's about loving yourself, no matter the shape you're in.
Dieting or losing weight is not the only way to be proactive about your health. Multiple studies have proven dieting, for the majority of people, simply does not work. THIS BLOG POST links to a slew of studies (not just articles hyping, but the actual statistical studies) showing most people lost all of 5-10 lbs, which they then gained back, regardless of the diet they tried. Diets don't make a person more healthy, either. Healthy habits lead to healthy bodies.
The fact is, what we know about nutrition and how the body utilizes it changes every day. One thing we do know is there is no one diet that works for everyone. Every person's body reacts differently based not only on their history and genetics, but also the history and genetics of their parents and grandparents. We don't even know how far back epigenetics affects us.
Regardless of medical history, there is no way convincing people to hate their bodies is in any way a path to health.
3. Health at every size seems physically impossible. It's true not every person is healthy at every size. People of all sizes have health issues. Just because a person is thinner or heavier than the socially acceptable norm does not mean they are unhealthy. People can eat a lot, be sedentary, and also be thin. People can be "morbidly obese" (the definition and history of this term would take far more space than this already overly long post, but we can get into it if you want) without medical indicators for diabetes, heart disease, joint issues, or any of the other red flags the author seems concerned with. Heart disease and high blood pressure really don't care about your height, weight, or BMI (another false indicator picked up and proliferated by the insurance industry).
Seriously, read the blog post linked above. It's one of about a million the author could have read to further her understanding, were she truly interested in understanding. Healthy habits = healthy bodies.
4. People are allowed to not be attracted to certain body types. There is nothing wrong with being attracted to, or not being attracted to certain body types. You don't have to lust after a larger woman. Her not being to your taste however does not give you the right to belittle that woman or tell her what she can or can't wear. This goes deeper than someone saying "no fatties" on their dating profile. No overweight person would want to date someone who reduced them to nothing more than a body size anyway. The focus is not on getting people to be attracted to larger body types, but on permitting people with larger body types the freedom to FEEL attractive. Today's society implies those with a Rubenesque figure should hate themselves, and anyone who finds them attractive should hate themselves as well.
This doesn't even address where our idea of attractive comes from, btw. Hello, Photoshop anyone?
5. Food addiction is a real medical problem. I agree we should address the fact our food supply and marketing industry is constructed to make us addicted and to over-consume. However, addicts almost never respond well to the interventions the author suggests. Telling a person they are fat, they eat the wrong things and they are killing themselves is not a revelation to them (and may not be true!). They heard these things already, many times, in many ways, all day every day. It's like telling someone they need to quit smoking. When has that ever really worked? The addict (if they are one) has to come to terms with their addiction on their own, in terms they alone can relate to. Only then can they make changes, and even then changes are not always successful.
And btw, not every overweight person is addicted to food. There are as many reason why a person is the size they are, as there are people in this world. The author may very well have one of several other food disorders, where she obsesses about everything she puts in her mouth. This just happens to be a socially acceptable disorder in that it makes her look more what we consider "normal". We won't even talk about the contradiction of her implying people are fat by choice, then bringing up food addiction.
6. We can't accept childhood obesity. I also agree that we have to teach children healthy eating habits at a young age. It bothers me to see infants and toddlers with full size candy bars and sodas. However, children of "normal" sized adults can and are obese. Just like adults, some children can consume candy and soda without ballooning to an unreasonable size. Some children have the same issues that cause obesity in adults. Making them hate themselves at a young age is certainly not the way to resolve whatever issues they are dealing with.
I see this article as complete bias against the Fat Acceptance Movement, wrapped in the pretense of a lack of understanding. If the author wanted to understand, there are blogs, studies, and articles galore that could help alleviate her misconceptions. I don't think she wants them alleviated though. I think she feels superior because she's always been "normal" sized, and as I indicated above, that gives her the right to pass judgement on anyone who does not fit her definition of "normal." This fits Merriam-Webster's definition of prejudice: "preconceived opinion that is not based on reason or actual experience." And THAT is why this article, and people's reaction to it, have touched a nerve.
TL;DR: The point of the fat acceptance movement, which the author completely misses, is that everyone on this earth should be appreciated and respected without shame, stigma, or oppression, no matter their size.