There is resistance in some corners of the fat acceptance community to considering any emotional factors involved in becoming and in being fat. As a Jungian, I pretty much do not think in terms of "mental illness" because I am more interested in what symptoms and problems mean than I am in diagnostic issues. But somewhere along the line, people began to conflate background emotional issues with mental illness. This is understandable as medicalization of all kinds of problems in living has pushed ordinary ups and downs in life into classification as a mental illness and this creates resistance to looking at them.
In my book I explore how fat became the target in the so-called “War on Obesity” and I write:
Pressure for this classification likely came from pharmaceutical companies and bariatric surgeons and other groups with an economic interest in gaining support for coverage of this “disease” by health insurance. One obesity researcher said in an interview with Rebecca Weinstein:
… there are several important implications of this decision. Classifying obesity as a disease, or a health condition that may be, at least in part, due to circumstances beyond an individual’s control, will open up the discussion to address it seriously and to persistently pursue all potential treatment options. It will help to overcome that barrier of blame and shame that currently occurs in the medical examination room. It will also force health insurance companies to consider covering its treatment. Additionally, treating it in a formal and standardized way will help evaluate and improve current standards of care. Lastly, classifying obesity as a disease will eventually create a medical support system for the treatment of obesity, which will, importantly, educate the public and put an end to the quackery that preys on obese individuals who are trying to lose weight every day. (Weinstein, Fat Kids: Truth and Consequences, 2014, pp. 104-105)
Her comment sounds reasonable until one considers that it classifies anyone above a certain BMI as diseased regardless of his or actual state of health. And it carries the assumption that being fat is something that should be treated, i.e. changed. Under this way of viewing obesity, treating fat can readily take priority over diagnosing and treating medical conditions that may or may not be related at all to weight. (The Fat Lady Sing, P. 15)
The battle to keep obesity out of classification as a disease was lost. But efforts to classify fat as a mental illness have not succeeded -- yet. There is no DSM V diagnosis for obesity. It is argued by some that being fat constitutes an eating disorder, based on the assumption, unquestioned and unchallenged, that fat people are compulsive eaters and in general eat differently from slender people. So some code it as Eating disorder not otherwise specified (EDNOS). There are fat people who are bulimic, anorexic, who eat compulsively. Just as there are slender people with the same issues. Weight alone is insufficient for diagnosis. I also do not believe that to be fat is to have an eating disorder.
I want to make clear that when I say I believe that there are emotional issues tied up in being fat and in becoming fat, I am not implying the presence of mental illness. Nor do I believe that identifying and working through those issues will lead to slenderness. But doing that work goes a long way toward body acceptance and being at home with oneself. And I firmly believe that dieting is not the answer. That therapists need to uncover their anti-fat bias. That fat people who choose to engage in psychotherapy have a right to expect to be met where they are and not be expected to meet the therapist’s agenda on weight.