'Biggest Loser' Trainer Settles The Diet-vs.-Exercise Debate Once And For All

It's not even a close match-up, says Bob Harper.

What's more important: diet or exercise?

You might expect a fitness expert to toe the line between the two, emphasizing the importance of balance rather than one over the other. But not Bob Harper -- not anymore, anyway.

Harper, a long-time trainer for "The Biggest Loser" and now the show's new host, says he is often approached by strangers seeking weight loss advice. As he tells "Oprah: Where Are They Now?", he used to avoid choosing sides, so to speak.

"I remember I would always just try to put a nice balance [to it]," Harper says.

Now, however, the 50-year-old fitness buff believes it's time for some real talk.

"It is all about your nutrition," he says. "It is 80 percent your nutrition; it is 20 percent fitness."

Catch Harper's full interview on this weekend's "Oprah: Where Are They Now?", airing Saturday, Feb. 13, at 10 p.m. ET on OWN.

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