Ruben Studdard went from the biggest winner to the biggest loser.

No, that’s not a dis. It’s reality. Well, reality TV.

He won “American Idol” in 2003 (sorry Clay Aiken), and last fall he landed on “The Biggest Loser,” dropping 119 pounds but, alas, not making it to the finals in February.

So which of those TV shows was more important in his life?

“I most definitely have to say ‘American Idol,’ ” said Studdard, who performs Sunday through Tuesday at the Dakota Jazz Club in Minneapolis. “There would have come a time in my life when I would have had to deal with my health issues whether I was on a sickbed or passed out somewhere. I thank God that wasn’t the case. I think ‘American Idol’ was so important to me because it helped me have faith in the impossible.”

Losing all that weight — he was 462 pounds when he jumped on the scales for “Biggest Loser” last October — has enabled him to make it through the offstage tasks.

“The weight loss most definitely gives me the energy to do the things that I have to do both before and after the show,” the 6-foot-3 singer said. “Most people don’t understand that our jobs don’t end after we get off of the stage. There are meet-and-greets and CD signings and things people expect in addition to the performance that I have to do.”

He’ll need the endurance, performing two shows a night at the Dakota with fellow R&B star Lalah Hathaway.

“We’ll do some duets, we’ll do some songs separately, we’ll bring each other off and on the stage,” Studdard said last week from Malaysia, where he was performing with hitmaker David Foster. “I think people will love our voices together.”

Album of love classics

Studdard will focus on material from his new and probably best-reviewed album, “Unconditional Love,” a collection of love songs belonging to his parents’ generation, produced by Foster, the maestro behind Celine Dion and Josh Groban.

But Studdard, 35, claims he knew all the tunes — including Teddy Pendergrass’ “Close the Door,” Paul McCartney’s “My Love” and the Carpenters’ “Close to You” — from records owned by his older brother and parents. The only number he wasn’t familiar with was Neil Diamond’s “Hello Again,” which sounds heavenly with his velvety tenor, compared to Diamond’s froggy baritone.

“My brother always told me when I was a child that I had an old soul,” Studdard explained, “because I was always so fond of music that wasn’t part of my generation.”

The oldest selection is “The Nearness of You,” a standard written by Hoagy Carmichael in 1938.

“I wanted to put a fresh spin on it,” the singer explained. “So I listened to Marvin Gaye the whole day I recorded that song. That arrangement is really based on how I thought Marvin would approach that song.”

The album also includes a Gaye tune, “If This World Were Mine,” which Studdard does as a duet with Hathaway. And there’s a number by her father, Donny Hathaway, “Love, Love, Love.” The 1970s soul star, who died 35 years ago, was one of Studdard’s idols.

“He was the first singer that I heard who merged the sound I grew up with in the church with a more clean, polished popular kind of sound,” said Studdard, whose 2004 album, “I Need an Angel,” was a gospel collection. “The first time I heard him — my father had a greatest hits album — I instantly fell in love with his voice and ever since I’ve had to find anything I could find with his voice on it.

“It’s really surreal to be on tour with his daughter because I feel the same way about her. She put the album out with Joe Sample [1999’s “The Song Lives On”], I think it was my junior year in college, and it really changed my life. I wanted to stretch my music, listening to her.”

Limited touring

Studdard’s music career has had its ups and downs. He’s actually put out six albums in 10 years but America, as Ryan Seacrest might say, may not know it.

He hasn’t had a pop hit since 2004’s “Sorry 2004” or an R&B triumph since 2006’s “Change Me.” Studdard has not toured extensively, though he starred in a 2008 road show of the Fats Waller musical “Ain’t Misbehavin’,” has traveled with David Foster & Friends on and off for six years, and teamed up with Aiken for a brief concert trek in 2010.

Of course, Aiken, who was “Idol” runner-up to Studdard by about 134,000 votes out of 24 million cast, is now running for Congress. Would Studdard campaign for him?

“I’m willing to do whatever Clay needs me to do for him,” said Studdard, who stays in touch with the North Carolina Democrat.

Would Studdard consider running for office?

“The only office I’m running for is trying to be the best singer in the world,” he said without hesitation.

He gives a little more thought to the current season of “American Idol” even though he hasn’t had a chance to watch much of it.

“People in Alabama are going crazy right now because there are three guys from my state still on the show,” said the longtime Birmingham resident. “Hopefully one of them will take the crown.”

While in Minneapolis, he’ll get a chance to see some of his cousins — the late Kenneth Saffold, a cousin and lawyer from Mendota Heights, was a Dakota Jazz Club regular for years — and likely hit the gym.

“I try to work out every day. Maybe an hour, hour and a half,” Studdard said. “It’s mostly cardio because you need endurance. I do that at least six times a week. I have made it a part of my lifestyle.”