A certain orange-haired clown might want to look away as Vikings coach Mike Zimmer is asked to name the biggest difference between today's rookies and the ones who entered the NFL back when he did a quarter-­century ago.

"The biggest thing I would say that's changed since I started is guys [back then] would eat McDonald's and all that stuff," Zimmer said Tuesday as training camp opened for 37 rookies, select young veterans and quarterbacks. "These guys [today] are pretty careful about what they put in their bodies and the nutrition aspect. The weightlifting and all the different things they do now is much more sophisticated. The sleep, all the recovery things they do."

To test this theory, let's sit down with the 90th man on the Vikings' 90-man roster. Hastings native Tiano Pupungatoa, a 23-year-old undrafted rookie from South Dakota State, became that last guy in when he was signed Monday to take the roster spot of waived running back Roc Thomas.

"Everyone I know is of the same mind-set when it comes to following a diet," said Pupungatoa, a 6-4, 308-pound left guard. "Everybody has their own little tweaks to their diet, but they still have one they follow.

"It's part of the competition to make it in this league. If you're not moving forward, you're stepping backward."

Video (03:12) Vikings general manager Rick Spielman talked to the press as rookies and quarterbacks began their first practice of training camp Tuesday.

Before his pro-day training began earlier this year, Pupungatoa went to see Dr. Michael Kim, a California physician who partners with the big fella's agent. To keep Pupungatoa's weight at an athletic 307 to 310, Kim prescribed a high-protein, high-fat diet.

Unless you're 20-something and play offensive line, do not try this at home.

"It's between 4,900 and 5,200 calories a day," Pupungatoa said. "Except when I was working my landscaping job at Green Street Landscaping in Stillwater. Then it was 6,000 to 7,000 calories a day because I was working 40 hours a week and working out four days a week at Horsepower Strength & Conditioning in Fridley."

Pupungatoa went to River Falls High School. His family still lives in River Falls. And, yes, he grew up a Packers fan because his dad, Finau, was an even bigger Packers fan. At least until two days ago.

"When I signed," said Pupungatoa, "my dad said, 'That's OK. I'll throw all my Packers stuff away, and let's go buy some purple.' "

And keep eating. A lot.

For breakfast, Pupungatoa eats 12 eggs.

"I eat them as fast as possible so I don't feel like throwing up," he said. "I used to do scrambled, but I do hard-boiled now. It's easier to eat them fast."

And for lunch and dinner?

"By noon, I try to do 16 to 24 ounces of steak with maybe bacon and wheat toast," Pupungatoa said. "Then dinner is one or two steaks or a whole chicken with some sweet potatoes. I add sweet potatoes into all my meals because they're super whole foods. And a lot of milk and some super whole-food snacks throughout the day."

Per Dr. Kim's orders, Pupungatoa also is allowed one "cheat meal" a week.

"I'll go looking for any Chinese buffet, Korean buffet, Mongolian barbecue," Pupungatoa said. "Wherever I can get the most bang for the buck."

The calories don't appear to be slowing Pupungatoa down. He looks lean while the Vikings stayed interested and in contact with him from the time he went through their rookie minicamp in April until signing him.

"He was an athletic kid who showed up," General Manager Rick Spielman said.

Pupungatoa got the call Friday to drive over Monday. With time in the car and a cheat meal to burn, he made a pit stop at Culver's in River Falls.

"It's about 35 minutes to get over here," he said. "I ordered four double butter burgers with cheese and ate them on the way."

Hey, even the most sophisticated 21st century players deserve a throwback meal once a week.

Mark Craig is an NFL and Vikings Insider. Twitter: @markcraigNFL. E-mail: mcraig@startribune.com