This prospective study quantified the weight change in 20 consecutive patients undergoing total knee arthroplasty. Resected bone, soft tissues, and bone reamings were collected during surgery and weighed using a digital scale at the end of the procedure. Results were compared to the cumulative weights of the prosthesis, bone cement, patellar component, and polyethylene liner. Average weight of the resected bone and soft tissues was 167.71 g for men and 130.13 g for women. Mean weight of the implanted prosthesis and cement used was 509.92 g for men and 422.56 g for women. Men tended to receive a larger-sized prosthesis than women. Overall, the average weight gain as a result of knee arthroplasty was 345.54 g for men and 292.44 g for women. This translates to an insignificant increase in body weight.