I'm Scared I Will Gain Weight After A Cholecystectomy. I

I'm scared I will gain weight after a cholecystectomy. I don't eat greasy foods now (never really have). I've lost 10 lbs this past year by exercising & watching my diet and I don't want to regain this weight, if I have this surgery.
how necessary is this surgery if I don't really have digestive issues, but have had an ultrasound where stones were present?