Per ESPN's Baxter Holmes, Pelicans general manager David Griffin said Williamson put on eight pounds of muscle in just one week during a teamwide heavy weightlifting routine this offseason.
"He's not normal," Griffin said "So finding stasis with Zion is the challenge, because he's 19 years old. He's still growing. It's not going to be about a number. It's going to be about metrics of flexibility and strength and control and all of the different things that we can measure that really are outside of weight."
During Williamson's brief appearance in the summer league, some analysts were critical of his apparent lack of conditioning.
ESPN's Seth Greenberg said on First Take in July that Williamson was "not in shape" and "significantly overweight."
When Williamson underwent knee surgery in October to repair a torn meniscus, Griffin disputed any notion the 19-year-old was injured because he was in poor physical condition.
"The notion that this happened because Zion is in poor condition is asinine," he told reporters. "He wasn't in poor condition when he went 12-of-13 last week against Utah. That's not what it is. He's just a very unique body type and certainly from a physics perspective."
Holmes cited a study by sports science lab P3 from the end of the 2018-19 regular season that determined the four biggest factors that contributed to serious knee injuries. The first three factors were how the foot rotates over the course of a jump; how the femur rotates relative to the shin; and the ability to control landing from a jump using the hips.
The fourth factor, mass, "has no independent relationship to risk of injury," the study found. Williamson told ESPN's Jorge Sedano (h/t Andrew Lopez of ESPN) on Dec. 25 that the Pelicans were tweaking the way he runs and walks, and Holmes noted the intent is to manage the first three factors that contribute to knee injuries and control body mass.
All of the work New Orleans and Williamson have been doing behind the scenes could be put on display in games starting next week. Griffin told reporters Wednesday the No. 1 pick in the 2019 NBA draft is expected to make his professional debut Jan. 22 against the San Antonio Spurs.