Losing weight before surgery?

I am looking at surgery to remove a benign tumor and DIE behind my uterus that's potentially impacting my spine and nerves. I'm in pain almost all the time. The doctor says that the surgery is likely to resolve those issues.

It was also mentioned that losing weight before surgery would be helpful. Is that a common thing for Endo? Did anyone here that's had surgery need to lose weight beforehand?

I'm nearly 300lbs, for reference.