Serena Williams is showing off her 31-pound weight loss after going on the GLP-1 medication Ro. "I feel great," Williams, 43, told People in an interview published on Thursday, August 21. "I feel really good and healthy. I feel light physically and light mentally." The retired tennis pro explained that she decided to try weight-loss medication because she was "never" able to reach the weight she "needed" after giving birth to daughter Olympia in 2017.