Pat Riley, who already has published one book (`Showtime") this season, says to look for another one at your bookstore soon.

"I'm going to call it `The Playoff Diet Book,"' said the Los Angeles Lakers coach. "How to lose 19 pounds by worrying your way to an NBA title."When the NBA playoffs began nearly two months ago, Riley weighed 210 pounds, his usual weight.

When they ended last night, with his Lakers victorious in the championship game over the Detroit Pistons, he weighed 191 pounds.

"In the playoffs I fast a lot," he said. "I just don't eat much. It makes me hungrier to succeed, I guess. I don't talk much either, or go out to restaurants for dinner or anything like that. I don't even open the mail. For all I know we don't have any money left. I'll have to check with my wife.

"If I don't focus completely on the championship," he said, "I feel guilty. I don't feel like I'm doing everything I can."

This year, especially, Riley didn't feel he had the luxury of easing up once the playoffs hit. It was his big mouth that "guaranteed" a second straight championship for the Lakers just minutes after they'd won the 1987 NBA title a year ago in Boston.

Tuesday night, after the Lakers had nipped Detroit in a seven game series after also needing seven games to get past the Utah Jazz and Dallas Mavericks in earlier playoff rounds, Riley finally had that worry off his back.

"I never once regretted saying it," he said of the guarantee. But he allowed that, as Great Guarantees go, it hardly deserves to now take a place alongside the legendary promises in the history of sport.

"I think people like Joe Namath and Muhammad Ali, they really meant it when they did their predictions," said Riley. "Mine didn't have the same intent. Mine was a challenge to this team. I wanted to create some pressure. I think ours is a team that responds well to pressure."

He didn't want his Lakers to become the 19th straight NBA champion to not repeat. He wanted them to have his guarantee to have to live up to.

"We've been playing for these championships all through the '80s," he said. "And until you lose one you don't know the misery. Once you do you get real serious about not letting it happen again. You realize that at this stage that's all it is - success and misery.

"This team has talent," he said after his guarantee had been validified Tuesday night. "But what sets it apart is its heart and character. That's what people will remember about this team."

With that he was off to the locker room for a champagne shower, and, after that, a pressure-free late-night dinner.

As for the future, he wasn't saying anything. At least not for the moment.

"What if he goes out tomorrow and guarantees three in a row?" a reporter asked Kareem Abdul-Jabbar, the Lakers' captain.

"He won't be able to do that," said Kareem.

"Why not?"

"The team would get to him first."