Often, medical treatment has to balance the overall benefit and life expectancy of the patient. When resources are limited or expensive, someone with several problems may be considered less likely to benefit from expensive treatment for one problem when another problem makes the treatment just a stop gap before the other life threatening problem drags their health down even more.
However a recent article suggests that in the case of a kidney transplant, obese patients are just as likely to make good progress as normal or thin patients. The risk of death over the next year decreases by about 66% in obese patients who receive a transplant, compared to obese patients staying on dialysis. This is very much the same as for non-obese patients.
This report on some recent research seems to contradict earlier research which suggested that obese patients on dialysis did better than thin patients and worse after a transplant.
You can read the article here; the research was conducted at the University of British Columbia and St. Paul's Hospital in Vancouver, Canada.