The delivery box that carries a three-day sampling of meals from the weight-loss company Jenny Craig is tantalizingly large. Inside is a plastic-foam box containing a supply of what looks like candy: seven mysteriously labeled Anytime Bars and another treat known as a Yogurt Dream Bar. Jenny Craig would appear to be the Willy Wonka of weight-loss regimes, promising the magic of sweets that make you thin; the package also holds a brownie and a puff-pastry twist and a bag of chips. Finally, there are meals, packaged in sky blue: among them, French toast and an egg scramble and macaroni and cheese.

That is the Jenny Craig of America; then there is the Jenny Craig of France, where Nestlé, which purchased the company in 2006, started marketing its product two years ago. The French Jenny Craig box is smaller, its interior container more elegant. Instead of white foam, the packaging is brightly patterned, like a chic shopping bag. Inside, there are dishes like boeuf bourguignon and velouté de tomates. The meals seem more grown-up and sophisticated than the American versions, so many of which seem chosen to evoke childhood favorites.

Selling an American-style weight-loss program to France would seem an absurd business proposition: from a French point of view, Americans might appear better equipped to give pointers on how to gain weight than how to lose it. The obesity rate in the United States is around 35 percent, compared with 14.5 percent in France. But the rate of increase in France has been worrying: in 1997, the obesity rate in France was only 8.5 percent. The government has initiated a series of antiobesity measures meant to restore traditional healthy eating habits (including last year a near ban on ketchup in school cafeterias). France’s obesity concerns still pale in comparison with this country’s. “We will never catch up to America,” Erick Moreau, the director of Jenny Craig in Europe, assured me. Nonetheless, French women do get fat, increasingly so, and so do men — 38 percent of the adult population there is now considered overweight. Jenny Craig in France currently has 4,000 active members, and many more have tried the service, Moreau says.

Jenny Craig is not the first weight-loss plan popular in America to make inroads in France. Weight Watchers, which first landed there in the ’70s, now has 1,800 weekly meetings. But Weight Watchers is a more natural transplant to a country proud of its cuisine: it does not dictate what clients eat, merely how much of it. Jenny Craig, on the other hand, with its individual microwaveable portions and heavy reliance (at least in the early phases) on prescribed, packaged foods, is not an obvious easy sell in a food culture based on fresh food from the market and communal meals. Jenny Craig’s approach to that challenge is to try to persuade clients that the plan is not a departure from French culture but a return to its fundamental values. To sell this novelty to the French requires convincing them that they are in fact resisting rather than succumbing to the inexorable influence of American eating habits — that the American scourge of obesity can still be neutralized by the power of French tradition, even if that tradition comes in the form of vacuum-sealed, shelf-stabilized products.