Sabathia, 30, was 21-7 last season with a 3.18 ERA in 34 starts, marking his first 20-win season and tying for the American League lead in victories.
But after undergoing arthroscopic surgery to repair cartilage damage in his right knee, Sabathia dropped 25 pounds over the winter in part by cutting Cap'n Crunch cereal -- which he used to eat by the box -- out of his diet.
Sabathia also linked with a nutritionist and a personal chef, and twice-daily cardio workouts helped reduce his weight to 290 pounds -- finally, his listed weight on the back of his baseball card is accurate.
"It was the knee and just me getting older, not feeling the same way as I did when I was 25," Sabathia said. "It was the combination of both of those things, and trying to pitch as long as I can and not have that affect me."
The results were immediately noticeable to Sabathia, who said that his stamina improved and that his knee -- which required a hidden brace for his postseason starts -- was no longer presenting an issue. He lost inches off his waistline but nothing off his fastball.
"I'm a big guy. I've always been a big guy and I'm going to be a big guy," Sabathia said. "This was just something to try to help extend my career. With me turning 30, having the knee surgery, I thought it was the right time to try to come in and take some pressure off of that."
Sabathia's also planning on continuing to take stress away from a rotation that needs him to be its leader.
In four Grapefruit League starts, Sabathia was 1-0 with a 3.31 ERA spanning 16 1/3 innings. He allowed 17 hits and six earned runs, walking three and striking out 10.
"He just knows how to pitch," catcher Russell Martin said. "He knows how to mix up his pitches, he can throw all of his pitches for strikes at any time. He's just a smart pitcher.
"He doesn't give in when he doesn't need to, and he's just aggressive and not afraid to throw strikes. He's just got ace stuff."
This will mark Sabathia's eighth career Opening Day start, having drawn the honors five times with the Cleveland Indians, as well as in each of his first two seasons with New York.
His first couple of openers in a Yankees uniform hasn't gone as well as Sabathia might have hoped.
In his 2009 debut, Sabathia was hit for six runs in 4 1/3 innings by the Orioles in a losing effort, and he then took a no-decision in the first game played at Yankee Stadium as the Indians defeated the Yankees, 10-2.
Last season, Sabathia took a no-decision on Opening Day at Fenway Park, allowing five runs in 5 1/3 innings to the Red Sox. It's a trend he'll look to reverse against Detroit, a lineup he was 1-1 against in two starts last season.
"This is New York; you always want to go out and try to win," Sabathia said. "Every year is different, so I'll go out and try to do the same thing I did last year, just try to give the team a chance to win every time out."