In “Selective Eating,” Jean-Denis Vigne, of France’s National Museum of Natural History, concludes that the Paleolithic diet is “more inspired by the myth of the noble savage than by the realities revealed by science,” and that humans are adaptable omnivores.

Choosy eating interferes with another key aspect of French mealtimes: the shared experience of food. In France, “eating does not have the sole purpose of nourishing the biological body but also and above all of nourishing the social bond,” writes the social psychologist Estelle Masson in “Selective Eating.”

This can seem excessively formal. When I invited some French families over to eat pizza and watch a soccer match on TV, they automatically assembled at my dining-room table for a sit-down meal. (I had foolishly envisioned eating pizza on the couch.)

We Anglophones have reasons for adopting strange diets. Increasingly, we live alone. We have an unprecedented choice of foods, and we’re not sure what’s in them, or whether they’re good for us. And we expect to customize practically everything: parenting, news, medicines, even our own faces.

Anyway, we’re not trying to have a shared experience of food. Mr. Fischler says that in his focus groups, Americans often described eating as part of an individual journey of self-discovery, in which each person tries to “find out over time and experience what my true nutritional self is, and satisfy it.”

But selective eating may not lead us to our best selves. Since I’ve lived in France, there’s been a march of studies pointing to the wisdom of what the French have been doing all along. Apparently it’s fine to eat some cheese, butter, chocolate and red meat; diets rarely work; and to lose weight, you should exercise more and eat less. Mr. Fischler is currently studying the health impact of eating together by looking at buffet tables at Club Med and the American “freshman 15.”

Eating among the French certainly affected me. After a few years here, I gave up most of my selective food habits. I still wouldn’t eat a dog’s penis, but I have tried oysters. It turns out that the best part of going with the food flow isn’t the health benefits or the cuisine, it’s the conversation. You can finally talk about something else.