In total hip arthroplasty (THA), it is preferable that patients have an ideal preoperative Body Mass Index (within 20% of the normal). The purpose of this study is to determine whether patients maintain their preoperative reduced weight after THA and whether the effort of encouragement and cost of a dietician to lose weight preoperatively is worthwhile. Conducted over five years, this study included 100 patients with a mean age of 62.5 years (34 to 83). Preoperative and postoperative weights were obtained from clinical records. There was a postoperative weight increase in 51% of patients and a decrease in postoperative weight in 46%. Pre-operative weight was maintained in 3%.