They have the impression that being weighed means the doctor will immediately prescribe weight loss as a treatment to whatever ailment they initially came to the doctor for, whether it is a sore throat, a joint issue or a rash. It put the responsibility on the fat to lose weight without any immediate solution to the issue they have now that is causing them pain. I mean, it's not as if the doctor can't see that you're a huge fatass just by looking at you and prescribe you weight loss regardless, but I think when the doctor realises that the patient declines to be weighed because 'muh HAES', he/she just throws expensive drugs at the fatty just to shut them up.