But friends say the problem was more simple -- he just loved to eat.
Buffalo wings, hamburgers, ice cream and Pepsi were daily staples.
He stocked his office at the Metrodome with soda and snacks, telling visitors that everything in the place was fat free. It's full of fat, Puckett would joke, and it's all free.
On the mornings Puckett and his friend Sherm Leske fished, they always stopped for breakfast afterward. Leske would order eggs and toast, but Puckett always ordered two double cheeseburgers, a cola and dessert.
"I'd say, 'Kirby, you eat to live, you don't live to eat,' " Leske said. "And he just looked at me and gave me that [silly] grin."
Once Puckett called his divorce attorney, Bob Zalk, from a McDonald's drive-thru. "He's ordering all this food," Zalk said. "Whatever he ordered, he ordered two of them.
"I ask him, 'Who is all there with you?' And he says, 'Nobody. It's all mine.' "
On July 12, 1996, Puckett announced his retirement. "Baseball's been a great part of my life," he said. "But now it's time for me to close this chapter of this book in baseball and go on with part two of my life. Kirby Puckett's going to be all right. Don't worry about me."
Friends say that they tried over the years to confront Puckett about his weight, but that they never had much success.
"I'd be as tactful as I could possibly be," Harris said. "How do you say to someone, 'I don't want you dying on me?' "
Puckett's longtime friend Darryl Hughes told him several times: "You can't continue like this."
When the warnings didn't work, Hughes said, he bought Puckett a subscription to a health magazine "to try and penetrate his psyche."
In 2004, Harris got Puckett a health club membership in hopes of encouraging him to exercise. On Puckett's first day in the gym, he hit the weights hard.
The next day, he called Harris at 7 a.m. to tell him that he was so sore from the workout that he couldn't even summon the strength to pop a few aspirin to relieve the pain.
You know all that stuff in my locker? Harris said Puckett told him. Give it all to charity. Because I'm not coming back.
"He didn't like to work out to work out," his friend Steve Stinski said. "There had to be a game involved. He needed a ball. ... He needed competition."