"Oy."

That's the collective sigh of weight-watching Jews from around the Bay Area upon learning of yet another way to fall off the dieting wagon.

Krispy Kreme Doughnuts in Northern California has gone kosher.

Last week, the Krispy Kreme in Union City became the last of a baker's dozen of local outlets to be certified as kosher.

The entire process for all 13 stores took about a year and a half, said Rabbi Ben-Tzion Welton, a coordinator for Vaad Hakashrus of Northern California, a local kosher-certification agency.

"We were kosher before L.A. was kosher," said Welton, who said the new standing for the doughnut stores involves ongoing inspections following supervision and "a little extra elbow grease" during a regular "boil-out" cleaning of each store's cooking vats.

"The kosherization was very simple," Welton said. "All their ingredients checked out."

The idea of approaching local Krispy Kreme outlets about going kosher started with Rabbi Yitzchok Feldman of Palo Alto's Congregation Emek Beracha, who is a member of Vaad Hakashrus' executive committee.

Hearing that some franchises on the East Coast were kosher, Feldman decided to investigate.

"I walked into the local Krispy Kreme here in Mountain View and talked to the manager and asked him whether he was interested," said Feldman. The manager was, and he referred Feldman to the corporate offices in Sacramento.

"First they tried just a few, then they decided, 'Let's just make them all kosher,'" Welton said.

More than 20 other stores in the 285-outlet chain are kosher, according to a company spokeswoman.

The process was relatively easy, Feldman agreed, noting that all the ingredients used to make the doughnuts come from just two company manufacturing plants.

"The corporate rules for Krispy Kreme are very compatible with how we like to do things," Feldman said. "They're not allowed to just run out and buy something through a retail store."

Loc Huyn, a manager at the Mountain View outlet, which has had kosher standing for about a year, said he gets three or four inquiries a week from customers asking about the certification.

At the newly certified Union City store, "I've never had anyone ask, 'Are you kosher certified?'" said manager Randy Blankenship, who watches up to 40,000 doughnuts head out the door each day.

Still, he said, "it's good to do it, and I'm glad we did it."

Feldman predicted that the certification would be greeted enthusiastically by an untold number of kosher-observant families, many of whom hunger for more places to eat in the Bay Area. Now that Krispy Kreme has been added to the list, "it's something families can get some enjoyment out of," he said.

Feldman, a father of eight ranging in age from 3 months to 12 years, said, "Most of my kids enjoy them thoroughly."

He said the news also would be welcomed by some non-Jews, who view kosher standing as evidence of "a certain level of clean food.

"One should not think non-Jews are oblivious" to the kosher certification, he added.

The Bay Area also has gained another kosher establishment with the opening in January of Izzy's Brooklyn Bagels Too near Pac Bell Park. Izzy's has a Palo Alto location as well.

According to Welton, ongoing certification at Krispy Kreme will entail regular inspections. The cost is $1,200 annually for each outlet.

The kosher process will have no bearing on the caloric content of the treats, which are cooked in 100 percent vegetable shortening. According to Krispy Kreme's Web site, a basic glazed doughnut packs 200 calories (with 110 coming from fat). In contrast, one of its pumpkin spice old-fashioned varieties carries 340 calories (with 160 coming from fat)

Because as a Chabad rabbi Welton follows more rigorous kashrut practices, which involve consuming only kosher (chalav yisrael) milk products, "I haven't tasted them," he admitted. "I've drooled over them, but I haven't tasted them."