PORTLAND (AP) – A baker who lost half his business to the low-carb craze is cashing in on his dietary regime with a book based on the mathematical principles of the Golden Ratio, a formula used by Leonardo Da Vinci and made popular in “The Da Vinci Code.”

Stephen Lanzalotta created what he called the Da Vinci Diet in response to the decline in bread consumption brought on by the popularity of the Atkins Diet. The diet consists mostly of Mediterranean foods, including bread, fish, cheese, vegetables, meat, nuts and wine.

After hooking up with an agent, Lanzalotta last year signed a deal with Warner Books, a division of Time Warner Book Group, that included a six-figure advance.

Warner announced this week that the book, “The Diet Code: Revolutionary Weight-Loss Secrets from Da Vinci and The Golden Ratio,” will be the first in its new line of books called Warner Wellness, which will focus on health, fitness, relationships and similar topics. The book is scheduled for release in April 2006, with an announced first printing of 150,000 copies.

The diet is based on the Golden Ratio or Phi, a mathematical value that was used to built the pyramids and has since been found to exist most everywhere in nature.

Da Vinci is said to have used the Golden Ratio to proportion the human figures in his paintings – which is how it found its way into Dan Brown’s best-selling book.

“The basic premise is most universal patterns are based on the Golden Ratio, including our bodies,” Lanzalotta said Thursday in his bakery-restaurant, Sophia’s.

Warner, in announcing the new series, said Lanzalotta’s book is sure “to pique the interest of Da Vinci enthusiasts and weight-loss seekers alike.”

When Lanzalotta, 46, opened his Italian bakery in 2000, bread accounted for 80 percent of sales. But after the Atkins fad kicked in two years ago, bread dropped to just 20 percent of sales.

To make up for the decline, he expanded his menu with breakfast and Sunday brunch and by increasing his offerings of sandwiches and pastries.

Nowadays, his biggest sellers are combination plates – typically bread or polenta, cheese, olives, and braised chard or Italian cole slaw – featuring the basic mix of his diet: 20 percent protein, 52 percent carbohydrates and 28 percent fat.

Lanzalotta said his dietary regimen has helped him maintain a fit 160 pounds without giving up on the foods he loves.

In addition to the Da Vinci intrigue, the book’s cover promises to make the diet fun: “Eat bread, drink wine and lose weight.”