When society upholds dangerous standards of body types, people of all genders feel pressured to conform to them - even to the extent that they will develop an eating disorder or take dangerous weight-loss medications.
The argument
The argument works by identifying an incentive and then removing it. When society upholds dangerous standards of beauty, such as the potentially unattainable Kardashian-type body (skinny and curvy, somehow at the same time), this can push people to dangerous means to conform to societal pressures and achieve this body. That the standard is unattainable is central rather than incidental: a goal which cannot be reached by ordinary means invites extraordinary ones, because anybody who takes it seriously and fails by moderate methods is left only with immoderate ones. The harms that follow cover a wide range of severity. Some means can include eating disorders to lose weight, weight loss pills and teas that increase the metabolism at the risk of a heart attack, fad diets that are not scientifically backed, and potentially excessive plastic surgery. What these otherwise different behaviours share is that each is a coherent response to an incoherent demand — a person who believes their body must look a particular way, and who has been told by popular culture that it must, is acting consistently with that belief when they accept a medical risk in order to get there. This is where the body positivity movement makes its difference, and it does so upstream of the behaviour rather than by policing it. When people love their own bodies and are encouraged by popular culture to do so, this removes the incentive for people to go to exaggerated means to create their desired body for themselves. The intervention sits at the level of the standard rather than the symptom: warnings about diet pills or disordered eating address the harm once the motive is already in place, whereas a culture which presents a wider range of bodies as acceptable means fewer people acquire that motive at all. Judged by that effect, the movement has accomplished something practical rather than merely symbolic.
Premises
Counter-arguments
Instead of being an inclusive movement for all body types, body positivity has lead to a "reverse ideal body type" where being skinny is now shameful. This has caused an equally harmful movement where people strive to have the body types idealized by body positivity, sometimes to the extent where it costs them their own health or well-being.
Rejecting the premises
[Rejecting P1] The causal claim is broader than the evidence. Eating disorders are substantially heritable and multi-determined, and treating them as a response to beauty standards misstates the condition — anorexia predates mass media and appears across very different cultures. [Rejecting P2] The movement is not one thing. It spans personal self-acceptance, fat-acceptance activism and commercial marketing that borrows the language while selling the same products, and the premise credits the whole with the aims of its best version. [Rejecting P3] The incentive account does not fit how these behaviours work. Disordered eating is rarely a considered response to an incentive that encouragement could remove, and the counter-pattern is documented: a new ideal has emerged against which thinness itself draws criticism, carrying its own pressures. [Rejecting C] The conclusion asserts an effect no one has measured. Body dissatisfaction and eating-disorder presentations did not fall over the period the movement grew, which is at least in tension with the claim.