Megapastor and bestselling author Rick Warren believes he has an answer to America's obesity epidemic — and it lies in the Book of Daniel. (The full story appears in this week's issue of TIME, available to subscribers here .)

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Let’s say you believe in God (most Americans do). Let’s say you’re deeply religious (most Americans say they are). So what does God want for you? You can be pretty sure God wants you to be happy, to be charitable, to be honest, to be kind. You can be pretty sure God doesn’t care if you’re rich, beautiful, famous or thin, right? Well, that thin part may take a little explaining.

With the U.S. tottering under an obesity epidemic that has left two-thirds of all adults and one-third of all kids overweight or obese, public health experts are despairing of finding new ways to get Americans off their duffs, away from the fridge and back into at least nominally healthy habits. Fad diets are useless; gym memberships do nothing — at least if they go unused; public service ads get ignored. But, as we explore in this week’s issue of TIME (available to subscribers here), where all of those efforts have failed, faith could succeed — at least according to Pastor Rick Warren.

Two years ago, Warren, the author of the über-bestseller The Purpose Driven Life and the leader of the Saddleback mega-church in Lake Forest, Calif., was struck by how out of shape his 20,000-strong congregation had gotten and, he readily admitted, he was no better, tipping the scales at 295 lbs. — or a full 90 lbs. too much for his 6-ft.-3-in. frame. He suspected he had a way to fix all that — one that might work in the wider world as well — and the secret, he believed, lay in Scripture, specifically in the Book of Daniel.

(MORE: The Book of Daniel: Is It Really About Diet?)

There’s a lot that happens in the Book of Daniel, but the critical passage occurs when Daniel and three other Jewish boys are brought to the court of the conquering King Nebuchadnezzar, where they are to be fed and trained so that they may serve in the royal circle. But as the Biblical passage recounts, the boys resist at least in part, refusing the rich foods of the king’s table and choosing a more spartan fare instead:

…Daniel resolved not to defile himself with the royal food and wine, and he asked the chief official for permission not to defile himself this way… “Please test your servants for ten days: Give us nothing but vegetables to eat and water to drink. Then compare our appearance with that of the young men who eat the royal food, and treat your servants in accordance with what you see.”

What the chief official saw, of course, was that Daniel and his friends had grown fitter and stronger than the other servants. It wasn’t vegetarianism or vigorous exercise that had worked that magic — though those were part of it. Instead, it was a belief that it was impossible to serve God fully if you were out of shape or unwell. For Daniel, getting fit was a triumph of faith — and Warren was convinced his church members could find motivation the same way.

With that was born the Daniel Plan, a sweeping program of smart eating (and yes, lean meats are included), workout classes, small-group support meetings, walk and worship sessions and more, much of it made available both in person and online. Warren recruited three marquee names from the world of medicine — Drs. Mehmet Oz, Daniel Amen and Mark Hyman (all of different faiths) — to help spread the good-health message, and the Saddleback members fell in love with the plan. More than 15,000 of them have signed up so far and in the past 18 months alone, they have lost a collective 260,000 lbs.

(MORE: Dr. Oz: How Faith and Health Go Hand in Hand)

The bigger question about the Daniel Plan is whether it could work in other churches — both evangelical and non-evangelical — not to mention in synagogues, mosques and other houses of worship. Warren is betting it can, and, according to Hyman, is considering rolling out the program to 1 billion people worldwide over the next decade. Non-believers may grumble at the religious component of the plan, and Warren himself has stirred controversy over time with the strictness of his evangelical teachings. But this mission may transcend all of that. “We all get sick, regardless of religion,” says Hyman. When it comes to getting well, he and others argue, we can’t be choosy about where we get our answers.

Read the full story in this week’s issue of TIME, available to subscribers here.