After a photo of "The Eternals" star's buff body went viral, he shared his secret to becoming ripped on Thursday's show: "I have not had pizza or a doughnut in over a year. I've had no refined sugar in a year. I've had almost no carbs at all."
Nanjiani's new eating habits were implemented while he was training for Marvel's "The Eternals," which comes into theaters Nov. 6, 2020.
In response, Kimmel surprised Nanjiani with a dessert mobile filled with delicious treats and Guillermo even brought him a pizza.
At the end of the interview, Nanjiani took a bite of the pizza, ending his yearlong diet.
"Jimmy Kimmel Live!" airs weeknights on ABC and on the ABC app at 11:35 p.m.