(ABC News)

When I sat down with Pastor Rick Warren for "This Week, I asked him about his obvious weight loss since the last time I interviewed him. It turns out he has lost about 60 pounds in the last year alone and it all started with a baptism.

WARREN: On that particular day, I baptized 864 people.  It took me about four hours to do this. Now, at 150 pounds a person, I'm putting them under water.  That's about 50,000 pounds that I'm, you know, dunking.  Along about number 500, I had a thought. It wasn't a very spiritual thought.  It was, man, we're all fat. (LAUGHTER)

WARREN: And I thought, well, wait a minute, I'm fat. I'm a terrible example of this. This is not your father's Saddleback. We've been putting on weight. And of course, it's widely known that America is becoming more and more obese. So I thought I can't ask people to get in shape unless I do, and I'm a terrible model here.

WARREN: You know, I've always had an enormous amount of energy, more than even young guys, and I really didn't care what I looked like, so I didn't take care of my body. I just didn't. And I ate all I wanted. I was a purpose-driven eater. (LAUGHTER). And I - I just enjoyed eating all the time.  And I put the pounds on.

WARREN: And so the following Sunday, I stood up in front of people and I said, "I need to repent."  I said, "Now, you guys, I've only gained two or three pounds a year as your pastor.  But I've been your pastor 30 years.  (LAUGHTER) "And I need to lose 90 pounds. Does anybody else want to help out on this? And would you like to join me on this?"

WARREN: And we found a passage of scripture about Daniel, in the book of Daniel, where he ate healthy food and the king's people ate bad food and Daniel's people got healthy.  And I said, "We're going to call this the Daniel Plan."… I figured maybe 200 people in my church would sign up for this.  Twelve thousand.

TAPPER: Twelve thousand?

WARREN: Twelve thousand signed up for the Daniel Plan, and we did what was called 'Knowing Your Five,' your height, your weight, your waist, your blood pressure, and your cholesterol.  And we asked doctors in our church to set up about a dozen booths for three or four weeks and took people's blood and took their measurements and then they - we have a website called the DanielPlan.com.  And you could enter your numbers.  And we're tracking it together.

WARREN: Well, in the first year I've lost 60 pounds, and our church has lost over 250,000 pounds.

TAPPER: Two hundred fifty thousand - that's a whole mega-church itself.

WARREN: It's a mega-church. I said I'm looking for the day I can say that we've lost the equivalent of a jumbo jet. (LAUGHTER) And so now this next year we're involving other people in this plan, other churches that want to do it. Anybody can do it. They can go onto the DanielPlan.com.