Body positivity disincentivizes dangerous eating disorders and weight-loss initiatives
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. 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. 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.
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.