Giants coach Ben McAdoo on the sideline during preseason game...

Giants coach Ben McAdoo on the sideline during preseason game against the Jets at MetLife Stadium on Saturday, Aug. 27, 2016. Credit: George McNish

It was around the time Jim Fassel was about to work his first game as an NFL head coach when Ronnie Barnes took him aside, a look of concern etched on the Giants trainer’s face.

“Jim, are you feeling OK?” Barnes asked.

“I’m feeling fine, why?” Fassel responded.

Barnes asked Fassel how much he weighed. Fassel knew he had lost weight since taking the job in January 1997. He didn’t realize just how much until he stepped onto a scale.

“My normal weight is 205, 210, but I weighed 185,” Fassel said Wednesday, speaking from his home in Las Vegas. “I said, ‘Ronnie, I’m eating more than I’ve ever eaten in my life. I have snacks, I eat ice cream every night.’ Ronnie said, ‘You’re just burning it up. You have to try to relax a little bit. You’re all over the place.’ ”

Barnes even had Fassel get blood work done to rule out illness. The diagnosis: football obsession. Physically, Fassel was fine.

Fassel, a former offensive coordinator and Giants quarterbacks coach before being named to succeed Dan Reeves as head coach, had become consumed with the job in advance of his first game. As Ben McAdoo prepares for his own debut with the Giants nearly 20 years later, Fassel can relate to what he must be going through as he prepares for Sunday’s game against the Cowboys.

“You’re consumed with the job,” Fassel said. “I remember getting ready for that season, I had been working seven days a week, 6 a.m. to 11 p.m. regularly, and I took a vacation before training camp, and we went to the movies one night. My son John was sitting next to me, and at the end of the movie, he said, ‘Dad, you were in a daze.’ I said, ‘You think so?’ ”

John asked his father to name the movie they had just seen. Fassel couldn’t.

“He said I was just sitting there, looking at the screen,” Fassel said. “I had no recollection of anything that had happened in the movie.”

But Fassel also remembers being so focused and so prepared for his first game that he was more than ready for the challenge. “I had rehearsed things so much, and I did everything I wanted to do,” he said. “I didn’t even need the play chart in front of me. It was intense.”

The Giants beat the Eagles, 31-17, at Giants Stadium, and Fassel went on to lead the Giants to a 10-5-1 record and the NFC East championship. He was selected as the NFL’s Coach of the Year. He coached the Giants to Super Bowl XXXV after the 2000 season, and made the playoffs once more before he was fired after the 2003 season.

McAdoo can only hope for a similar start. McAdoo, who replaced two-time Super Bowl champion Tom Coughlin, admits to a mix of excitement and nervousness.

“I’m excited, champing at the bit,” McAdoo said. “Can’t wait for Sunday. It’s a long week. It’s good to get out here and go through our normal Wednesday practice, hit the pads tomorrow. I’ll take it one day, one play at a time, like the rest of the team.”

Will there be butterflies?

“If you don’t get a little anxious to go play and go coach,” he said, “you probably have to find something else to do. I think that’s normal. That’s healthy.”

As someone who also went from offensive coordinator to head coach, Fassel said McAdoo needs to be mindful of the bigger picture. Throw in the pressure of the New York market, and the challenge becomes even greater.

“That’s what he has to prove now,” Fassel said. “You’re an excellent coordinator, but now you have to handle the whole thing. Can you make the transition to be an overall manager, plus keep the offense where we expect you to keep it? The management is huge and it’s undervalued, especially in New York. You’re the face of the franchise. You need to be able to handle the media. If you’re a buffoon up there or you lose your composure, that’s going to reflect on the franchise, and the players are going to look at you and say, ‘Can you handle the whole tamale?’ ’’

McAdoo’s only misstep with the media has been showing up at his introductory news conference in an oversized sport jacket, setting off a social media stir. But since then McAdoo has shown the job isn’t too big for him.

Then again, he’ll get a better sense of whether that’s the case starting Sunday in Texas.

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