Usher has lifted the lid on how he transformed his body to look just like a boxing great.
The singer has turned actor to star as Sugar Ray Leonard in biopic Hands Of Stone, and set about his training regime very seriously.
He told People magazine: "When you're playing a role like this, you can't act a boxer. The only way you know what it is to be a boxer is to be one. I began to see a transformation happen with my body."
Usher explained that he had been training three times a day and following Dr Gundry's Matrix diet, that involved five or six small meals instead of three big ones, and eating healthy foods such as fish, blueberries and pisstachios.
He went on: "Once you clean your body out and really get accustomed to eating that type of food, you see the results and you feel better."
The Grammy winner said he's trying to stay healthy, but joked that he's working on a new role, Usher Ray, which has a slightly more lax regime.
"The first 20lbs are the hardest in the world," he said. "When you get into that year of work and you created goals and met them, you don't want to go back and completely fall off the wagon. But Usher Ray likes to have cookies on occasion."