[Content Note: Fat hatred, dehumanization, gaslighting.]
#1: Everyone who is fat is fat for the same reason.
Nope! There are a whole lot of reasons that fat people are fat—and "overeating" is only one of those many reasons. In fact, "overeating" itself even has to exist in combination with some other factor(s), because "overeating," which I'm putting in quotes because that word can mean anything from "eating more than the recommended number of calories for a person without any other medical problems of a specific size and activity level" to "eating more than I think that fat pig should be putting in hir mouth," is generally something, using the same definitions, that a lot of genetically thin people do, too. It's just that they don't get fat from it, so they aren't said to be "overeating." Just "eating."
Some fat people have a genetic disposition toward fatness. Some fat people are recovering from eating disorders and/or yo-yo dieting and/or addiction(s) that fucked up their metabolisms. Some fat people have disordered eating. Some fat people have illnesses that themselves cause weight gain and/or require meds which cause weight gain. Some fat people have disabilities that cause weight gain. Some fat people have chosen, consciously or unconsciously, fatness as a coping mechanism in response to abuse and/or sexual violence. Some fat people are poor and/or lack access to fresh foods. Some fat people have simply never been taught good eating habits for their individual bodies and/or don't have the ability or opportunity to prepare the sorts of meals their individual bodies need. Some fat people's bodies have been affected by environmental toxins that have been found to cause weight gain. Etc.
There are a whole lot of reasons that individual fat people are fat. Most of us have some combination of these factors. For the majority of us, it is not as simple as: "I eat too much and exercise too little and thus I am fat."
And when thin people (or other fat people) make some "calories in; calories out" argument, or any variation thereof that implies all fat people are fat for the same reason, and all of us could be thin(ner) if only we reduced calories absorbed and increased calories burned, if only we tried harder, that's the same bullshit bootstraps argument that conservatives make about marginalized people all the time.
Paul Campos, who has written extensively about the OH NOES Obesity Crisis! and has debunked many of the myths surrounding fat and health, once wrote in a column for the Rocky Mountain News, which no longer appears to be available online:
This inspires me to point something out to my more liberal readers. Remember that particularly clueless right-wing acquaintance of yours? The one who believes that anybody in America can become rich, because he thinks about poverty in a completely unscientific, anecdotal way, which allows him to treat the exceptional case as typical? The one who can’t seem to understand the simplest structural arguments about the nature of social inequality?The erroneous belief that all fat people are fat for the same reason, at the expense of acknowledging individual circumstances, is dehumanizing in the same way that blanket assumptions about any group is.
The next time you see some fat people and get disgusted by their failure to "take care of themselves," think about your clueless friend.
The only reason it's still considered acceptable, by people who should know better, to make such sweeping, dehumanizing statements about fatsronauts is because we still regard fatness as a behavior, and as an indicator of weak character, rather than as the neutral descriptor that it is.
Finally, there is this: Many fat people routinely speak up about the reality that our fat bodies aren't strictly a result of eating too much and exercising too little, and bravely tell the stories of our lives in which we share our personal circumstances, even knowing we will be mocked, dismissed, and disbelieved.
In order to continue to subscribe to the belief that fat people are all fat for the same reason, one must believe that those of us who speak to our own experiences which differ from that narrative are lying or delusional.
I, for one, am exhausted with the implication that I don't know my own body better than an observer who's invested in the idea that: 1. My fat is a problem; and 2. I'm not being diligent or honest about solving it.
If you're going to be an ally to fat people, Step One is acknowledging our individual humanity.
[Related Reading: On Fat Hatred and Eliminationism; Today in Fat Hatred; Proposed.]