Fat people are often denied knee replacement surgery – unless they can lose weight; which is just ridiculously stupid.

Denying fat people mobility will often lead them to be fatter. 

There is no way to achieve long term significant weight loss (except for a tiny fraction of the population); and often these attempts lead the dieter to not only regain the weight but end up fatter.

And guess what? 

There’s another study out that finds that being fat (overweight or obese) does not increase the risk of patient’s blood loss, transfusion risk, or immediate postoperative complications following simultaneous bilateral total knee arthroplasty (i.e., replacing both knees at the same time). 

https://pubmed.ncbi.nlm.nih.gov/32057638/

or

https://doi.org/10.1016/j.knee.2020.01.012

So what is standing between fat people who need knee surgery and new knees?

Fat bias. 

Doctor, heal thyself.