The companies employ chefs to craft alluring offers — Brake, for instance, has a partnership with Mr. Ducasse to enhance quality and create new recipes. Its lush catalog includes 3,500 items like frozen foie gras with caramelized apples or a precooked kit for gourmet beef stew with sous-vide meat, vegetables and broth.

Mr. Denamur, the activist, is concerned that many such dishes contain additives not found in fresh foods. One morning at Les Philosophes, he brandished an empty container that had held salt cod purée, which he said he had found in a rival restaurant’s trash bin. The ticket was stamped “like homemade,” but it also listed chemical preservatives. “This is why we need transparency,” he said.

But the argument isn’t really about preservatives; it’s about origins. “If a chef uses frozen onions to save time and costs, does that really need to be pointed out?” said Didier Chenet, the president of Synhorcat.

For the industry, the answer is no. “When you identify something as frozen, you put it in the head of the consumer that it might be less good,” said Ignace de Villepin, the marketing director of Davigel, said. “That is wrong, but they may be less inclined to choose it,” he said.

Davigel fought legislation requiring labels for frozen items, and Mr. deVillepin said he doubted that the fresh-foods lobby would succeed in reviving it. The most important thing, he said, was for diners is to know the origin of the food and to feel “that what is on my plate looks and tastes good, that I’m enjoying my experience in the restaurant, and I want to come back.”

Cordelia Dolan, 25, on a recent visit from London with five friends, was skeptical. As they paid the bill at Les Philosophes, they said they favored labels for frozen items — and would probably avoid them.

“You don’t want to eat something that you can buy in a shop,” she said. “That’s not why you go to restaurants.”