WASHINGTON—A bipartisan-looking coalition of Democratic governors announced today that they would ban whole grains in their states, effective immediately, hours after a federal nutrition guideline recommended eating them.

"Whole grains were fine until about nine o'clock this morning," said a spokesperson for the coalition, speaking from a podium decorated with a single loaf of white bread. "We reviewed the evidence, and the evidence is that someone else said it first."

The ban, signed in near-identical language by each governor within a 12-minute window, defines "whole grain" as "any grain that still has the rest of the grain on it," and carries a penalty of one stern letter. Legal analysts called the coordinated timing "remarkable" and noted that several states appeared to have used the same pen.

The federal recommendation, which urges Americans to eat two to four servings a day, was widely seen as uncontroversial until it was endorsed by the people who published it. Nutrition experts said the guideline is consistent with decades of research. They also said they had expected this.

"We want to be clear that we have nothing against fiber," the spokesperson added. "We just would like it to come from somewhere else." Asked where, the spokesperson said the coalition had formed a working group.

Bakeries in the affected states have reportedly begun selling whole-grain bread in plain paper bags labeled "bread," which regulators have agreed not to look at too closely. One baker said his customers have been polite about it. "They come in, whisper the name of the loaf, and leave," he said. "It's like a speakeasy, but healthy."

At press time, the coalition had endorsed a competing proposal to ban oatmeal, pending a review of who last said it was good for you.