The congregation exercises in their seats during a rally for pastor Rick Warren's “Daniel Plan” at Saddleback Church in Lake Forest, Calif. The rally was designed to prompt people to employ his diet and fitness program.

When Jim Black leads people on a robust walk three times a week on the grounds of the 120-acre Saddleback Church in Lake Forest, Calif., he’s got powerful company: God.

The several dozen people who join him have shown up with the same hopes that anyone brings to an exercise plan: They mean to lose weight, ditch inhalers, get stronger.

But at Saddleback, there’s a lot more going on. Pastor Rick Warren is using the power of his church, one of the biggest in the country, to impress upon his followers that their bodies need the same care as their spirits.

After two months on “the Daniel Plan,” Black gave up his diabetes medication. He has given up wheat, dairy and sugar. He recently bought a bicycle. In a year, he lost 90 pounds; his wife lost 40.

“It’s that one Scripture: My body is not my own, my body is on loan and someday I’ll have to account for it,” said Black, 48. “I wanted to serve God at a higher level. And I wanted to be able to fit in the seat of a roller coaster and buy one seat on the airplane instead of two.”

Despite a multibillion-dollar industry of programs and books and diet meals and meetings, the secular world has done a fairly lousy job at getting people to lose weight and get fit.

So why not turn to a higher power?

One Sunday afternoon, 3,000 people came to a rally at Saddleback to hear about the Daniel Plan from Warren and others, including two of its creators, Daniel Amen, a psychiatrist who belongs to Saddleback, and Dr. Mark Hyman, who has taken care of Bill and Hillary Clinton.

“If Jesus came to dinner, what would you feed him?” Hyman asked the crowd. “Would you give him a Big Mac, fries and a Coke? Would you feed him all the junk that we feed ourselves and our guests when they come to dinner? Or would you eat real food?”

Places of worship may call to mind ice cream socials or groaning tables of fried chicken and potato salad more than they do workouts, but Warren is the latest in a long line of people of faith connecting mind, body and spirit. After all, gluttony is one of the seven deadly sins.

They include the 19th Century health reformer Sylvester Graham and, later, the Seventh-day Adventist Dr. John Harvey Kellogg. More recently, fundamentalist C.S. Lovett’s “Help Lord — the Devil Wants Me Fat!” sold close to 100,000 copies in two years after its release in 1977. Other books have included “More of Jesus, Less of Me” and “Slim for Him.” And Warren is not alone in using as inspiration the story of the prophet Daniel, who rejected the rich food and wine of King Nebuchadnezzar.

“Millions of American Christians have made a religious duty out of diet,” R. Marie Griffith writes in her 2004 book “Born Again Bodies.”

“Fit bodies ostensibly signify fitter souls,” she said by phone. But they also can be used to support a male-dominated hierarchy; the market is lucrative, and it’s important to look at the underlying messages.

Warren has an opportunity to change lives, Griffith said. “Because of his name and his fame and how beloved and admired he is, his could really have a bigger impact.”

Dee Eastman, director of the Daniel Plan, said she doesn’t look at it as a diet plan. “Ultimately, we try to look toward getting balance in health overall. And we think food plays a huge role in that,” she said. “This is going to sound extreme, but if you can cut out the white menaces — white flour and white sugar — your palate changes and your cravings stop. You can actually start loving foods that love you back.”